All normal kernel memory is "TDX private memory". This includes
everything from kernel stacks to kernel text. Handling
exceptions on arbitrary accesses to kernel memory is essentially
impossible because they can happen in horribly nasty places like
kernel entry/exit. But, TDX hardware can theoretically _deliver_
a virtualization exception (#VE) on any access to private memory.
But, it's not as bad as it sounds. TDX can be configured to never
deliver these exceptions on private memory with a "TD attribute"
called ATTR_SEPT_VE_DISABLE. The guest has no way to *set* this
attribute, but it can check it.
Ensure ATTR_SEPT_VE_DISABLE is set in early boot. panic() if it
is unset. There is no sane way for Linux to run with this
attribute clear so a panic() is appropriate.
There's small window during boot before the check where kernel
has an early #VE handler. But the handler is only for port I/O
and will also panic() as soon as it sees any other #VE, such as
a one generated by a private memory access.
[ dhansen: Rewrite changelog and rebase on new tdx_parse_tdinfo().
Add Kirill's tested-by because I made changes since
he wrote this. ]
Fixes: 9a22bf6deb
("x86/traps: Add #VE support for TDX guest")
Reported-by: ruogui.ygr@alibaba-inc.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20221028141220.29217-3-kirill.shutemov%40linux.intel.com
789 lines
20 KiB
C
789 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (C) 2021-2022 Intel Corporation */
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#undef pr_fmt
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#define pr_fmt(fmt) "tdx: " fmt
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#include <linux/cpufeature.h>
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#include <asm/coco.h>
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#include <asm/tdx.h>
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#include <asm/vmx.h>
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#include <asm/insn.h>
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#include <asm/insn-eval.h>
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#include <asm/pgtable.h>
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/* TDX module Call Leaf IDs */
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#define TDX_GET_INFO 1
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#define TDX_GET_VEINFO 3
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#define TDX_ACCEPT_PAGE 6
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/* TDX hypercall Leaf IDs */
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#define TDVMCALL_MAP_GPA 0x10001
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/* MMIO direction */
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#define EPT_READ 0
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#define EPT_WRITE 1
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/* Port I/O direction */
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#define PORT_READ 0
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#define PORT_WRITE 1
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/* See Exit Qualification for I/O Instructions in VMX documentation */
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#define VE_IS_IO_IN(e) ((e) & BIT(3))
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#define VE_GET_IO_SIZE(e) (((e) & GENMASK(2, 0)) + 1)
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#define VE_GET_PORT_NUM(e) ((e) >> 16)
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#define VE_IS_IO_STRING(e) ((e) & BIT(4))
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#define ATTR_SEPT_VE_DISABLE BIT(28)
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/*
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* Wrapper for standard use of __tdx_hypercall with no output aside from
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* return code.
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*/
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static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
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{
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struct tdx_hypercall_args args = {
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.r10 = TDX_HYPERCALL_STANDARD,
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.r11 = fn,
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.r12 = r12,
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.r13 = r13,
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.r14 = r14,
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.r15 = r15,
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};
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return __tdx_hypercall(&args, 0);
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}
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/* Called from __tdx_hypercall() for unrecoverable failure */
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void __tdx_hypercall_failed(void)
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{
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panic("TDVMCALL failed. TDX module bug?");
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}
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/*
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* The TDG.VP.VMCALL-Instruction-execution sub-functions are defined
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* independently from but are currently matched 1:1 with VMX EXIT_REASONs.
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* Reusing the KVM EXIT_REASON macros makes it easier to connect the host and
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* guest sides of these calls.
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*/
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static u64 hcall_func(u64 exit_reason)
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{
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return exit_reason;
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}
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#ifdef CONFIG_KVM_GUEST
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long tdx_kvm_hypercall(unsigned int nr, unsigned long p1, unsigned long p2,
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unsigned long p3, unsigned long p4)
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{
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struct tdx_hypercall_args args = {
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.r10 = nr,
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.r11 = p1,
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.r12 = p2,
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.r13 = p3,
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.r14 = p4,
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};
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return __tdx_hypercall(&args, 0);
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}
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EXPORT_SYMBOL_GPL(tdx_kvm_hypercall);
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#endif
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/*
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* Used for TDX guests to make calls directly to the TD module. This
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* should only be used for calls that have no legitimate reason to fail
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* or where the kernel can not survive the call failing.
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*/
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static inline void tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
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struct tdx_module_output *out)
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{
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if (__tdx_module_call(fn, rcx, rdx, r8, r9, out))
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panic("TDCALL %lld failed (Buggy TDX module!)\n", fn);
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}
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static void tdx_parse_tdinfo(u64 *cc_mask)
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{
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struct tdx_module_output out;
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unsigned int gpa_width;
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u64 td_attr;
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/*
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* TDINFO TDX module call is used to get the TD execution environment
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* information like GPA width, number of available vcpus, debug mode
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* information, etc. More details about the ABI can be found in TDX
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* Guest-Host-Communication Interface (GHCI), section 2.4.2 TDCALL
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* [TDG.VP.INFO].
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*/
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tdx_module_call(TDX_GET_INFO, 0, 0, 0, 0, &out);
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/*
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* The highest bit of a guest physical address is the "sharing" bit.
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* Set it for shared pages and clear it for private pages.
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*
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* The GPA width that comes out of this call is critical. TDX guests
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* can not meaningfully run without it.
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*/
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gpa_width = out.rcx & GENMASK(5, 0);
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*cc_mask = BIT_ULL(gpa_width - 1);
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/*
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* The kernel can not handle #VE's when accessing normal kernel
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* memory. Ensure that no #VE will be delivered for accesses to
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* TD-private memory. Only VMM-shared memory (MMIO) will #VE.
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*/
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td_attr = out.rdx;
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if (!(td_attr & ATTR_SEPT_VE_DISABLE))
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panic("TD misconfiguration: SEPT_VE_DISABLE attibute must be set.\n");
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}
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/*
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* The TDX module spec states that #VE may be injected for a limited set of
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* reasons:
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*
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* - Emulation of the architectural #VE injection on EPT violation;
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*
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* - As a result of guest TD execution of a disallowed instruction,
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* a disallowed MSR access, or CPUID virtualization;
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*
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* - A notification to the guest TD about anomalous behavior;
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*
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* The last one is opt-in and is not used by the kernel.
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*
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* The Intel Software Developer's Manual describes cases when instruction
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* length field can be used in section "Information for VM Exits Due to
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* Instruction Execution".
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*
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* For TDX, it ultimately means GET_VEINFO provides reliable instruction length
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* information if #VE occurred due to instruction execution, but not for EPT
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* violations.
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*/
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static int ve_instr_len(struct ve_info *ve)
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{
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switch (ve->exit_reason) {
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case EXIT_REASON_HLT:
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case EXIT_REASON_MSR_READ:
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case EXIT_REASON_MSR_WRITE:
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case EXIT_REASON_CPUID:
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case EXIT_REASON_IO_INSTRUCTION:
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/* It is safe to use ve->instr_len for #VE due instructions */
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return ve->instr_len;
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case EXIT_REASON_EPT_VIOLATION:
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/*
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* For EPT violations, ve->insn_len is not defined. For those,
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* the kernel must decode instructions manually and should not
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* be using this function.
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*/
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WARN_ONCE(1, "ve->instr_len is not defined for EPT violations");
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return 0;
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default:
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WARN_ONCE(1, "Unexpected #VE-type: %lld\n", ve->exit_reason);
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return ve->instr_len;
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}
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}
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static u64 __cpuidle __halt(const bool irq_disabled, const bool do_sti)
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{
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struct tdx_hypercall_args args = {
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.r10 = TDX_HYPERCALL_STANDARD,
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.r11 = hcall_func(EXIT_REASON_HLT),
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.r12 = irq_disabled,
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};
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/*
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* Emulate HLT operation via hypercall. More info about ABI
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* can be found in TDX Guest-Host-Communication Interface
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* (GHCI), section 3.8 TDG.VP.VMCALL<Instruction.HLT>.
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*
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* The VMM uses the "IRQ disabled" param to understand IRQ
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* enabled status (RFLAGS.IF) of the TD guest and to determine
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* whether or not it should schedule the halted vCPU if an
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* IRQ becomes pending. E.g. if IRQs are disabled, the VMM
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* can keep the vCPU in virtual HLT, even if an IRQ is
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* pending, without hanging/breaking the guest.
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*/
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return __tdx_hypercall(&args, do_sti ? TDX_HCALL_ISSUE_STI : 0);
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}
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static int handle_halt(struct ve_info *ve)
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{
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/*
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* Since non safe halt is mainly used in CPU offlining
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* and the guest will always stay in the halt state, don't
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* call the STI instruction (set do_sti as false).
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*/
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const bool irq_disabled = irqs_disabled();
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const bool do_sti = false;
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if (__halt(irq_disabled, do_sti))
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return -EIO;
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return ve_instr_len(ve);
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}
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void __cpuidle tdx_safe_halt(void)
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{
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/*
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* For do_sti=true case, __tdx_hypercall() function enables
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* interrupts using the STI instruction before the TDCALL. So
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* set irq_disabled as false.
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*/
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const bool irq_disabled = false;
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const bool do_sti = true;
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/*
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* Use WARN_ONCE() to report the failure.
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*/
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if (__halt(irq_disabled, do_sti))
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WARN_ONCE(1, "HLT instruction emulation failed\n");
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}
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static int read_msr(struct pt_regs *regs, struct ve_info *ve)
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{
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struct tdx_hypercall_args args = {
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.r10 = TDX_HYPERCALL_STANDARD,
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.r11 = hcall_func(EXIT_REASON_MSR_READ),
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.r12 = regs->cx,
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};
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/*
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* Emulate the MSR read via hypercall. More info about ABI
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* can be found in TDX Guest-Host-Communication Interface
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* (GHCI), section titled "TDG.VP.VMCALL<Instruction.RDMSR>".
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*/
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if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
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return -EIO;
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regs->ax = lower_32_bits(args.r11);
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regs->dx = upper_32_bits(args.r11);
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return ve_instr_len(ve);
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}
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static int write_msr(struct pt_regs *regs, struct ve_info *ve)
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{
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struct tdx_hypercall_args args = {
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.r10 = TDX_HYPERCALL_STANDARD,
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.r11 = hcall_func(EXIT_REASON_MSR_WRITE),
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.r12 = regs->cx,
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.r13 = (u64)regs->dx << 32 | regs->ax,
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};
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/*
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* Emulate the MSR write via hypercall. More info about ABI
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* can be found in TDX Guest-Host-Communication Interface
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* (GHCI) section titled "TDG.VP.VMCALL<Instruction.WRMSR>".
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*/
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if (__tdx_hypercall(&args, 0))
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return -EIO;
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return ve_instr_len(ve);
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}
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static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve)
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{
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struct tdx_hypercall_args args = {
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.r10 = TDX_HYPERCALL_STANDARD,
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.r11 = hcall_func(EXIT_REASON_CPUID),
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.r12 = regs->ax,
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.r13 = regs->cx,
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};
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/*
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* Only allow VMM to control range reserved for hypervisor
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* communication.
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*
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* Return all-zeros for any CPUID outside the range. It matches CPU
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* behaviour for non-supported leaf.
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*/
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if (regs->ax < 0x40000000 || regs->ax > 0x4FFFFFFF) {
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regs->ax = regs->bx = regs->cx = regs->dx = 0;
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return ve_instr_len(ve);
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}
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/*
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* Emulate the CPUID instruction via a hypercall. More info about
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* ABI can be found in TDX Guest-Host-Communication Interface
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* (GHCI), section titled "VP.VMCALL<Instruction.CPUID>".
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*/
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if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
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return -EIO;
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/*
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* As per TDX GHCI CPUID ABI, r12-r15 registers contain contents of
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* EAX, EBX, ECX, EDX registers after the CPUID instruction execution.
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* So copy the register contents back to pt_regs.
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*/
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regs->ax = args.r12;
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regs->bx = args.r13;
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regs->cx = args.r14;
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regs->dx = args.r15;
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return ve_instr_len(ve);
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}
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static bool mmio_read(int size, unsigned long addr, unsigned long *val)
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{
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struct tdx_hypercall_args args = {
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.r10 = TDX_HYPERCALL_STANDARD,
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.r11 = hcall_func(EXIT_REASON_EPT_VIOLATION),
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.r12 = size,
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.r13 = EPT_READ,
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.r14 = addr,
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.r15 = *val,
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};
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if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
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return false;
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*val = args.r11;
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return true;
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}
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static bool mmio_write(int size, unsigned long addr, unsigned long val)
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{
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return !_tdx_hypercall(hcall_func(EXIT_REASON_EPT_VIOLATION), size,
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EPT_WRITE, addr, val);
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}
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static int handle_mmio(struct pt_regs *regs, struct ve_info *ve)
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{
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unsigned long *reg, val, vaddr;
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char buffer[MAX_INSN_SIZE];
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struct insn insn = {};
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enum mmio_type mmio;
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int size, extend_size;
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u8 extend_val = 0;
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/* Only in-kernel MMIO is supported */
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if (WARN_ON_ONCE(user_mode(regs)))
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return -EFAULT;
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if (copy_from_kernel_nofault(buffer, (void *)regs->ip, MAX_INSN_SIZE))
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return -EFAULT;
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if (insn_decode(&insn, buffer, MAX_INSN_SIZE, INSN_MODE_64))
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return -EINVAL;
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mmio = insn_decode_mmio(&insn, &size);
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if (WARN_ON_ONCE(mmio == MMIO_DECODE_FAILED))
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return -EINVAL;
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if (mmio != MMIO_WRITE_IMM && mmio != MMIO_MOVS) {
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reg = insn_get_modrm_reg_ptr(&insn, regs);
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if (!reg)
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return -EINVAL;
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}
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/*
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* Reject EPT violation #VEs that split pages.
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*
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* MMIO accesses are supposed to be naturally aligned and therefore
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* never cross page boundaries. Seeing split page accesses indicates
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* a bug or a load_unaligned_zeropad() that stepped into an MMIO page.
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*
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* load_unaligned_zeropad() will recover using exception fixups.
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*/
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vaddr = (unsigned long)insn_get_addr_ref(&insn, regs);
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if (vaddr / PAGE_SIZE != (vaddr + size - 1) / PAGE_SIZE)
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return -EFAULT;
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|
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/* Handle writes first */
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switch (mmio) {
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case MMIO_WRITE:
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memcpy(&val, reg, size);
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if (!mmio_write(size, ve->gpa, val))
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return -EIO;
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return insn.length;
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case MMIO_WRITE_IMM:
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val = insn.immediate.value;
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if (!mmio_write(size, ve->gpa, val))
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return -EIO;
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return insn.length;
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case MMIO_READ:
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case MMIO_READ_ZERO_EXTEND:
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|
case MMIO_READ_SIGN_EXTEND:
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/* Reads are handled below */
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break;
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case MMIO_MOVS:
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|
case MMIO_DECODE_FAILED:
|
|
/*
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|
* MMIO was accessed with an instruction that could not be
|
|
* decoded or handled properly. It was likely not using io.h
|
|
* helpers or accessed MMIO accidentally.
|
|
*/
|
|
return -EINVAL;
|
|
default:
|
|
WARN_ONCE(1, "Unknown insn_decode_mmio() decode value?");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Handle reads */
|
|
if (!mmio_read(size, ve->gpa, &val))
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return -EIO;
|
|
|
|
switch (mmio) {
|
|
case MMIO_READ:
|
|
/* Zero-extend for 32-bit operation */
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|
extend_size = size == 4 ? sizeof(*reg) : 0;
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|
break;
|
|
case MMIO_READ_ZERO_EXTEND:
|
|
/* Zero extend based on operand size */
|
|
extend_size = insn.opnd_bytes;
|
|
break;
|
|
case MMIO_READ_SIGN_EXTEND:
|
|
/* Sign extend based on operand size */
|
|
extend_size = insn.opnd_bytes;
|
|
if (size == 1 && val & BIT(7))
|
|
extend_val = 0xFF;
|
|
else if (size > 1 && val & BIT(15))
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|
extend_val = 0xFF;
|
|
break;
|
|
default:
|
|
/* All other cases has to be covered with the first switch() */
|
|
WARN_ON_ONCE(1);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (extend_size)
|
|
memset(reg, extend_val, extend_size);
|
|
memcpy(reg, &val, size);
|
|
return insn.length;
|
|
}
|
|
|
|
static bool handle_in(struct pt_regs *regs, int size, int port)
|
|
{
|
|
struct tdx_hypercall_args args = {
|
|
.r10 = TDX_HYPERCALL_STANDARD,
|
|
.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
|
|
.r12 = size,
|
|
.r13 = PORT_READ,
|
|
.r14 = port,
|
|
};
|
|
u64 mask = GENMASK(BITS_PER_BYTE * size, 0);
|
|
bool success;
|
|
|
|
/*
|
|
* Emulate the I/O read via hypercall. More info about ABI can be found
|
|
* in TDX Guest-Host-Communication Interface (GHCI) section titled
|
|
* "TDG.VP.VMCALL<Instruction.IO>".
|
|
*/
|
|
success = !__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT);
|
|
|
|
/* Update part of the register affected by the emulated instruction */
|
|
regs->ax &= ~mask;
|
|
if (success)
|
|
regs->ax |= args.r11 & mask;
|
|
|
|
return success;
|
|
}
|
|
|
|
static bool handle_out(struct pt_regs *regs, int size, int port)
|
|
{
|
|
u64 mask = GENMASK(BITS_PER_BYTE * size, 0);
|
|
|
|
/*
|
|
* Emulate the I/O write via hypercall. More info about ABI can be found
|
|
* in TDX Guest-Host-Communication Interface (GHCI) section titled
|
|
* "TDG.VP.VMCALL<Instruction.IO>".
|
|
*/
|
|
return !_tdx_hypercall(hcall_func(EXIT_REASON_IO_INSTRUCTION), size,
|
|
PORT_WRITE, port, regs->ax & mask);
|
|
}
|
|
|
|
/*
|
|
* Emulate I/O using hypercall.
|
|
*
|
|
* Assumes the IO instruction was using ax, which is enforced
|
|
* by the standard io.h macros.
|
|
*
|
|
* Return True on success or False on failure.
|
|
*/
|
|
static int handle_io(struct pt_regs *regs, struct ve_info *ve)
|
|
{
|
|
u32 exit_qual = ve->exit_qual;
|
|
int size, port;
|
|
bool in, ret;
|
|
|
|
if (VE_IS_IO_STRING(exit_qual))
|
|
return -EIO;
|
|
|
|
in = VE_IS_IO_IN(exit_qual);
|
|
size = VE_GET_IO_SIZE(exit_qual);
|
|
port = VE_GET_PORT_NUM(exit_qual);
|
|
|
|
|
|
if (in)
|
|
ret = handle_in(regs, size, port);
|
|
else
|
|
ret = handle_out(regs, size, port);
|
|
if (!ret)
|
|
return -EIO;
|
|
|
|
return ve_instr_len(ve);
|
|
}
|
|
|
|
/*
|
|
* Early #VE exception handler. Only handles a subset of port I/O.
|
|
* Intended only for earlyprintk. If failed, return false.
|
|
*/
|
|
__init bool tdx_early_handle_ve(struct pt_regs *regs)
|
|
{
|
|
struct ve_info ve;
|
|
int insn_len;
|
|
|
|
tdx_get_ve_info(&ve);
|
|
|
|
if (ve.exit_reason != EXIT_REASON_IO_INSTRUCTION)
|
|
return false;
|
|
|
|
insn_len = handle_io(regs, &ve);
|
|
if (insn_len < 0)
|
|
return false;
|
|
|
|
regs->ip += insn_len;
|
|
return true;
|
|
}
|
|
|
|
void tdx_get_ve_info(struct ve_info *ve)
|
|
{
|
|
struct tdx_module_output out;
|
|
|
|
/*
|
|
* Called during #VE handling to retrieve the #VE info from the
|
|
* TDX module.
|
|
*
|
|
* This has to be called early in #VE handling. A "nested" #VE which
|
|
* occurs before this will raise a #DF and is not recoverable.
|
|
*
|
|
* The call retrieves the #VE info from the TDX module, which also
|
|
* clears the "#VE valid" flag. This must be done before anything else
|
|
* because any #VE that occurs while the valid flag is set will lead to
|
|
* #DF.
|
|
*
|
|
* Note, the TDX module treats virtual NMIs as inhibited if the #VE
|
|
* valid flag is set. It means that NMI=>#VE will not result in a #DF.
|
|
*/
|
|
tdx_module_call(TDX_GET_VEINFO, 0, 0, 0, 0, &out);
|
|
|
|
/* Transfer the output parameters */
|
|
ve->exit_reason = out.rcx;
|
|
ve->exit_qual = out.rdx;
|
|
ve->gla = out.r8;
|
|
ve->gpa = out.r9;
|
|
ve->instr_len = lower_32_bits(out.r10);
|
|
ve->instr_info = upper_32_bits(out.r10);
|
|
}
|
|
|
|
/*
|
|
* Handle the user initiated #VE.
|
|
*
|
|
* On success, returns the number of bytes RIP should be incremented (>=0)
|
|
* or -errno on error.
|
|
*/
|
|
static int virt_exception_user(struct pt_regs *regs, struct ve_info *ve)
|
|
{
|
|
switch (ve->exit_reason) {
|
|
case EXIT_REASON_CPUID:
|
|
return handle_cpuid(regs, ve);
|
|
default:
|
|
pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
|
|
return -EIO;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Handle the kernel #VE.
|
|
*
|
|
* On success, returns the number of bytes RIP should be incremented (>=0)
|
|
* or -errno on error.
|
|
*/
|
|
static int virt_exception_kernel(struct pt_regs *regs, struct ve_info *ve)
|
|
{
|
|
switch (ve->exit_reason) {
|
|
case EXIT_REASON_HLT:
|
|
return handle_halt(ve);
|
|
case EXIT_REASON_MSR_READ:
|
|
return read_msr(regs, ve);
|
|
case EXIT_REASON_MSR_WRITE:
|
|
return write_msr(regs, ve);
|
|
case EXIT_REASON_CPUID:
|
|
return handle_cpuid(regs, ve);
|
|
case EXIT_REASON_EPT_VIOLATION:
|
|
return handle_mmio(regs, ve);
|
|
case EXIT_REASON_IO_INSTRUCTION:
|
|
return handle_io(regs, ve);
|
|
default:
|
|
pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
|
|
return -EIO;
|
|
}
|
|
}
|
|
|
|
bool tdx_handle_virt_exception(struct pt_regs *regs, struct ve_info *ve)
|
|
{
|
|
int insn_len;
|
|
|
|
if (user_mode(regs))
|
|
insn_len = virt_exception_user(regs, ve);
|
|
else
|
|
insn_len = virt_exception_kernel(regs, ve);
|
|
if (insn_len < 0)
|
|
return false;
|
|
|
|
/* After successful #VE handling, move the IP */
|
|
regs->ip += insn_len;
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool tdx_tlb_flush_required(bool private)
|
|
{
|
|
/*
|
|
* TDX guest is responsible for flushing TLB on private->shared
|
|
* transition. VMM is responsible for flushing on shared->private.
|
|
*
|
|
* The VMM _can't_ flush private addresses as it can't generate PAs
|
|
* with the guest's HKID. Shared memory isn't subject to integrity
|
|
* checking, i.e. the VMM doesn't need to flush for its own protection.
|
|
*
|
|
* There's no need to flush when converting from shared to private,
|
|
* as flushing is the VMM's responsibility in this case, e.g. it must
|
|
* flush to avoid integrity failures in the face of a buggy or
|
|
* malicious guest.
|
|
*/
|
|
return !private;
|
|
}
|
|
|
|
static bool tdx_cache_flush_required(void)
|
|
{
|
|
/*
|
|
* AMD SME/SEV can avoid cache flushing if HW enforces cache coherence.
|
|
* TDX doesn't have such capability.
|
|
*
|
|
* Flush cache unconditionally.
|
|
*/
|
|
return true;
|
|
}
|
|
|
|
static bool try_accept_one(phys_addr_t *start, unsigned long len,
|
|
enum pg_level pg_level)
|
|
{
|
|
unsigned long accept_size = page_level_size(pg_level);
|
|
u64 tdcall_rcx;
|
|
u8 page_size;
|
|
|
|
if (!IS_ALIGNED(*start, accept_size))
|
|
return false;
|
|
|
|
if (len < accept_size)
|
|
return false;
|
|
|
|
/*
|
|
* Pass the page physical address to the TDX module to accept the
|
|
* pending, private page.
|
|
*
|
|
* Bits 2:0 of RCX encode page size: 0 - 4K, 1 - 2M, 2 - 1G.
|
|
*/
|
|
switch (pg_level) {
|
|
case PG_LEVEL_4K:
|
|
page_size = 0;
|
|
break;
|
|
case PG_LEVEL_2M:
|
|
page_size = 1;
|
|
break;
|
|
case PG_LEVEL_1G:
|
|
page_size = 2;
|
|
break;
|
|
default:
|
|
return false;
|
|
}
|
|
|
|
tdcall_rcx = *start | page_size;
|
|
if (__tdx_module_call(TDX_ACCEPT_PAGE, tdcall_rcx, 0, 0, 0, NULL))
|
|
return false;
|
|
|
|
*start += accept_size;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Inform the VMM of the guest's intent for this physical page: shared with
|
|
* the VMM or private to the guest. The VMM is expected to change its mapping
|
|
* of the page in response.
|
|
*/
|
|
static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc)
|
|
{
|
|
phys_addr_t start = __pa(vaddr);
|
|
phys_addr_t end = __pa(vaddr + numpages * PAGE_SIZE);
|
|
|
|
if (!enc) {
|
|
/* Set the shared (decrypted) bits: */
|
|
start |= cc_mkdec(0);
|
|
end |= cc_mkdec(0);
|
|
}
|
|
|
|
/*
|
|
* Notify the VMM about page mapping conversion. More info about ABI
|
|
* can be found in TDX Guest-Host-Communication Interface (GHCI),
|
|
* section "TDG.VP.VMCALL<MapGPA>"
|
|
*/
|
|
if (_tdx_hypercall(TDVMCALL_MAP_GPA, start, end - start, 0, 0))
|
|
return false;
|
|
|
|
/* private->shared conversion requires only MapGPA call */
|
|
if (!enc)
|
|
return true;
|
|
|
|
/*
|
|
* For shared->private conversion, accept the page using
|
|
* TDX_ACCEPT_PAGE TDX module call.
|
|
*/
|
|
while (start < end) {
|
|
unsigned long len = end - start;
|
|
|
|
/*
|
|
* Try larger accepts first. It gives chance to VMM to keep
|
|
* 1G/2M SEPT entries where possible and speeds up process by
|
|
* cutting number of hypercalls (if successful).
|
|
*/
|
|
|
|
if (try_accept_one(&start, len, PG_LEVEL_1G))
|
|
continue;
|
|
|
|
if (try_accept_one(&start, len, PG_LEVEL_2M))
|
|
continue;
|
|
|
|
if (!try_accept_one(&start, len, PG_LEVEL_4K))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
void __init tdx_early_init(void)
|
|
{
|
|
u64 cc_mask;
|
|
u32 eax, sig[3];
|
|
|
|
cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]);
|
|
|
|
if (memcmp(TDX_IDENT, sig, sizeof(sig)))
|
|
return;
|
|
|
|
setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
|
|
|
|
cc_set_vendor(CC_VENDOR_INTEL);
|
|
tdx_parse_tdinfo(&cc_mask);
|
|
cc_set_mask(cc_mask);
|
|
|
|
/*
|
|
* All bits above GPA width are reserved and kernel treats shared bit
|
|
* as flag, not as part of physical address.
|
|
*
|
|
* Adjust physical mask to only cover valid GPA bits.
|
|
*/
|
|
physical_mask &= cc_mask - 1;
|
|
|
|
x86_platform.guest.enc_cache_flush_required = tdx_cache_flush_required;
|
|
x86_platform.guest.enc_tlb_flush_required = tdx_tlb_flush_required;
|
|
x86_platform.guest.enc_status_change_finish = tdx_enc_status_changed;
|
|
|
|
pr_info("Guest detected\n");
|
|
}
|