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c726200dd1
linux/arch/arm64/include/asm/kvm_emulate.h
Christoffer Dall c726200dd1 KVM: arm/arm64: Allow reporting non-ISV data aborts to userspace 
For a long time, if a guest accessed memory outside of a memslot using
any of the load/store instructions in the architecture which doesn't
supply decoding information in the ESR_EL2 (the ISV bit is not set), the
kernel would print the following message and terminate the VM as a
result of returning -ENOSYS to userspace:

  load/store instruction decoding not implemented

The reason behind this message is that KVM assumes that all accesses
outside a memslot is an MMIO access which should be handled by
userspace, and we originally expected to eventually implement some sort
of decoding of load/store instructions where the ISV bit was not set.

However, it turns out that many of the instructions which don't provide
decoding information on abort are not safe to use for MMIO accesses, and
the remaining few that would potentially make sense to use on MMIO
accesses, such as those with register writeback, are not used in
practice.  It also turns out that fetching an instruction from guest
memory can be a pretty horrible affair, involving stopping all CPUs on
SMP systems, handling multiple corner cases of address translation in
software, and more.  It doesn't appear likely that we'll ever implement
this in the kernel.

What is much more common is that a user has misconfigured his/her guest
and is actually not accessing an MMIO region, but just hitting some
random hole in the IPA space.  In this scenario, the error message above
is almost misleading and has led to a great deal of confusion over the
years.

It is, nevertheless, ABI to userspace, and we therefore need to
introduce a new capability that userspace explicitly enables to change
behavior.

This patch introduces KVM_CAP_ARM_NISV_TO_USER (NISV meaning Non-ISV)
which does exactly that, and introduces a new exit reason to report the
event to userspace.  User space can then emulate an exception to the
guest, restart the guest, suspend the guest, or take any other
appropriate action as per the policy of the running system.

Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2019-10-21 18:59:44 +01:00

483 lines
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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012,2013 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* Derived from arch/arm/include/kvm_emulate.h
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.com>
*/
#ifndef __ARM64_KVM_EMULATE_H__
#define __ARM64_KVM_EMULATE_H__
#include <linux/kvm_host.h>
#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmio.h>
#include <asm/ptrace.h>
#include <asm/cputype.h>
#include <asm/virt.h>
unsigned long *vcpu_reg32(const struct kvm_vcpu *vcpu, u8 reg_num);
unsigned long vcpu_read_spsr32(const struct kvm_vcpu *vcpu);
void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v);
bool kvm_condition_valid32(const struct kvm_vcpu *vcpu);
void kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr);
void kvm_inject_undefined(struct kvm_vcpu *vcpu);
void kvm_inject_vabt(struct kvm_vcpu *vcpu);
void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_undef32(struct kvm_vcpu *vcpu);
void kvm_inject_dabt32(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_pabt32(struct kvm_vcpu *vcpu, unsigned long addr);
static inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
{
return !(vcpu->arch.hcr_el2 & HCR_RW);
}
static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
if (is_kernel_in_hyp_mode())
vcpu->arch.hcr_el2 |= HCR_E2H;
if (cpus_have_const_cap(ARM64_HAS_RAS_EXTN)) {
/* route synchronous external abort exceptions to EL2 */
vcpu->arch.hcr_el2 |= HCR_TEA;
/* trap error record accesses */
vcpu->arch.hcr_el2 |= HCR_TERR;
}
if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
vcpu->arch.hcr_el2 |= HCR_FWB;
if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features))
vcpu->arch.hcr_el2 &= ~HCR_RW;
/*
* TID3: trap feature register accesses that we virtualise.
* For now this is conditional, since no AArch32 feature regs
* are currently virtualised.
*/
if (!vcpu_el1_is_32bit(vcpu))
vcpu->arch.hcr_el2 |= HCR_TID3;
if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) ||
vcpu_el1_is_32bit(vcpu))
vcpu->arch.hcr_el2 |= HCR_TID2;
}
static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu->arch.hcr_el2;
}
static inline void vcpu_clear_wfe_traps(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 &= ~HCR_TWE;
}
static inline void vcpu_set_wfe_traps(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 |= HCR_TWE;
}
static inline void vcpu_ptrauth_enable(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK);
}
static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 &= ~(HCR_API | HCR_APK);
}
static inline void vcpu_ptrauth_setup_lazy(struct kvm_vcpu *vcpu)
{
if (vcpu_has_ptrauth(vcpu))
vcpu_ptrauth_disable(vcpu);
}
static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu)
{
return vcpu->arch.vsesr_el2;
}
static inline void vcpu_set_vsesr(struct kvm_vcpu *vcpu, u64 vsesr)
{
vcpu->arch.vsesr_el2 = vsesr;
}
static inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.pc;
}
static inline unsigned long *__vcpu_elr_el1(const struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu_gp_regs(vcpu)->elr_el1;
}
static inline unsigned long vcpu_read_elr_el1(const struct kvm_vcpu *vcpu)
{
if (vcpu->arch.sysregs_loaded_on_cpu)
return read_sysreg_el1(SYS_ELR);
else
return *__vcpu_elr_el1(vcpu);
}
static inline void vcpu_write_elr_el1(const struct kvm_vcpu *vcpu, unsigned long v)
{
if (vcpu->arch.sysregs_loaded_on_cpu)
write_sysreg_el1(v, SYS_ELR);
else
*__vcpu_elr_el1(vcpu) = v;
}
static inline unsigned long *vcpu_cpsr(const struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.pstate;
}
static inline bool vcpu_mode_is_32bit(const struct kvm_vcpu *vcpu)
{
return !!(*vcpu_cpsr(vcpu) & PSR_MODE32_BIT);
}
static inline bool kvm_condition_valid(const struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return kvm_condition_valid32(vcpu);
return true;
}
static inline void vcpu_set_thumb(struct kvm_vcpu *vcpu)
{
*vcpu_cpsr(vcpu) |= PSR_AA32_T_BIT;
}
/*
* vcpu_get_reg and vcpu_set_reg should always be passed a register number
* coming from a read of ESR_EL2. Otherwise, it may give the wrong result on
* AArch32 with banked registers.
*/
static inline unsigned long vcpu_get_reg(const struct kvm_vcpu *vcpu,
u8 reg_num)
{
return (reg_num == 31) ? 0 : vcpu_gp_regs(vcpu)->regs.regs[reg_num];
}
static inline void vcpu_set_reg(struct kvm_vcpu *vcpu, u8 reg_num,
unsigned long val)
{
if (reg_num != 31)
vcpu_gp_regs(vcpu)->regs.regs[reg_num] = val;
}
static inline unsigned long vcpu_read_spsr(const struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return vcpu_read_spsr32(vcpu);
if (vcpu->arch.sysregs_loaded_on_cpu)
return read_sysreg_el1(SYS_SPSR);
else
return vcpu_gp_regs(vcpu)->spsr[KVM_SPSR_EL1];
}
static inline void vcpu_write_spsr(struct kvm_vcpu *vcpu, unsigned long v)
{
if (vcpu_mode_is_32bit(vcpu)) {
vcpu_write_spsr32(vcpu, v);
return;
}
if (vcpu->arch.sysregs_loaded_on_cpu)
write_sysreg_el1(v, SYS_SPSR);
else
vcpu_gp_regs(vcpu)->spsr[KVM_SPSR_EL1] = v;
}
static inline bool vcpu_mode_priv(const struct kvm_vcpu *vcpu)
{
u32 mode;
if (vcpu_mode_is_32bit(vcpu)) {
mode = *vcpu_cpsr(vcpu) & PSR_AA32_MODE_MASK;
return mode > PSR_AA32_MODE_USR;
}
mode = *vcpu_cpsr(vcpu) & PSR_MODE_MASK;
return mode != PSR_MODE_EL0t;
}
static inline u32 kvm_vcpu_get_hsr(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.esr_el2;
}
static inline int kvm_vcpu_get_condition(const struct kvm_vcpu *vcpu)
{
u32 esr = kvm_vcpu_get_hsr(vcpu);
if (esr & ESR_ELx_CV)
return (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT;
return -1;
}
static inline unsigned long kvm_vcpu_get_hfar(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.far_el2;
}
static inline phys_addr_t kvm_vcpu_get_fault_ipa(const struct kvm_vcpu *vcpu)
{
return ((phys_addr_t)vcpu->arch.fault.hpfar_el2 & HPFAR_MASK) << 8;
}
static inline u64 kvm_vcpu_get_disr(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.disr_el1;
}
static inline u32 kvm_vcpu_hvc_get_imm(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_hsr(vcpu) & ESR_ELx_xVC_IMM_MASK;
}
static inline bool kvm_vcpu_dabt_isvalid(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_ISV);
}
static inline unsigned long kvm_vcpu_dabt_iss_nisv_sanitized(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_hsr(vcpu) & (ESR_ELx_CM | ESR_ELx_WNR | ESR_ELx_FSC);
}
static inline bool kvm_vcpu_dabt_issext(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SSE);
}
static inline int kvm_vcpu_dabt_get_rd(const struct kvm_vcpu *vcpu)
{
return (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SRT_MASK) >> ESR_ELx_SRT_SHIFT;
}
static inline bool kvm_vcpu_dabt_iss1tw(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_S1PTW);
}
static inline bool kvm_vcpu_dabt_iswrite(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WNR) ||
kvm_vcpu_dabt_iss1tw(vcpu); /* AF/DBM update */
}
static inline bool kvm_vcpu_dabt_is_cm(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_CM);
}
static inline int kvm_vcpu_dabt_get_as(const struct kvm_vcpu *vcpu)
{
return 1 << ((kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SAS) >> ESR_ELx_SAS_SHIFT);
}
/* This one is not specific to Data Abort */
static inline bool kvm_vcpu_trap_il_is32bit(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_IL);
}
static inline u8 kvm_vcpu_trap_get_class(const struct kvm_vcpu *vcpu)
{
return ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu));
}
static inline bool kvm_vcpu_trap_is_iabt(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_IABT_LOW;
}
static inline u8 kvm_vcpu_trap_get_fault(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_hsr(vcpu) & ESR_ELx_FSC;
}
static inline u8 kvm_vcpu_trap_get_fault_type(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_hsr(vcpu) & ESR_ELx_FSC_TYPE;
}
static inline bool kvm_vcpu_dabt_isextabt(const struct kvm_vcpu *vcpu)
{
switch (kvm_vcpu_trap_get_fault(vcpu)) {
case FSC_SEA:
case FSC_SEA_TTW0:
case FSC_SEA_TTW1:
case FSC_SEA_TTW2:
case FSC_SEA_TTW3:
case FSC_SECC:
case FSC_SECC_TTW0:
case FSC_SECC_TTW1:
case FSC_SECC_TTW2:
case FSC_SECC_TTW3:
return true;
default:
return false;
}
}
static inline int kvm_vcpu_sys_get_rt(struct kvm_vcpu *vcpu)
{
u32 esr = kvm_vcpu_get_hsr(vcpu);
return ESR_ELx_SYS64_ISS_RT(esr);
}
static inline bool kvm_is_write_fault(struct kvm_vcpu *vcpu)
{
if (kvm_vcpu_trap_is_iabt(vcpu))
return false;
return kvm_vcpu_dabt_iswrite(vcpu);
}
static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu)
{
return vcpu_read_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
}
static inline bool kvm_arm_get_vcpu_workaround_2_flag(struct kvm_vcpu *vcpu)
{
return vcpu->arch.workaround_flags & VCPU_WORKAROUND_2_FLAG;
}
static inline void kvm_arm_set_vcpu_workaround_2_flag(struct kvm_vcpu *vcpu,
bool flag)
{
if (flag)
vcpu->arch.workaround_flags |= VCPU_WORKAROUND_2_FLAG;
else
vcpu->arch.workaround_flags &= ~VCPU_WORKAROUND_2_FLAG;
}
static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu)) {
*vcpu_cpsr(vcpu) |= PSR_AA32_E_BIT;
} else {
u64 sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1);
sctlr |= (1 << 25);
vcpu_write_sys_reg(vcpu, sctlr, SCTLR_EL1);
}
}
static inline bool kvm_vcpu_is_be(struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return !!(*vcpu_cpsr(vcpu) & PSR_AA32_E_BIT);
return !!(vcpu_read_sys_reg(vcpu, SCTLR_EL1) & (1 << 25));
}
static inline unsigned long vcpu_data_guest_to_host(struct kvm_vcpu *vcpu,
unsigned long data,
unsigned int len)
{
if (kvm_vcpu_is_be(vcpu)) {
switch (len) {
case 1:
return data & 0xff;
case 2:
return be16_to_cpu(data & 0xffff);
case 4:
return be32_to_cpu(data & 0xffffffff);
default:
return be64_to_cpu(data);
}
} else {
switch (len) {
case 1:
return data & 0xff;
case 2:
return le16_to_cpu(data & 0xffff);
case 4:
return le32_to_cpu(data & 0xffffffff);
default:
return le64_to_cpu(data);
}
}
return data; /* Leave LE untouched */
}
static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
unsigned long data,
unsigned int len)
{
if (kvm_vcpu_is_be(vcpu)) {
switch (len) {
case 1:
return data & 0xff;
case 2:
return cpu_to_be16(data & 0xffff);
case 4:
return cpu_to_be32(data & 0xffffffff);
default:
return cpu_to_be64(data);
}
} else {
switch (len) {
case 1:
return data & 0xff;
case 2:
return cpu_to_le16(data & 0xffff);
case 4:
return cpu_to_le32(data & 0xffffffff);
default:
return cpu_to_le64(data);
}
}
return data; /* Leave LE untouched */
}
static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr)
{
if (vcpu_mode_is_32bit(vcpu))
kvm_skip_instr32(vcpu, is_wide_instr);
else
*vcpu_pc(vcpu) += 4;
/* advance the singlestep state machine */
*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
}
/*
* Skip an instruction which has been emulated at hyp while most guest sysregs
* are live.
*/
static inline void __hyp_text __kvm_skip_instr(struct kvm_vcpu *vcpu)
{
*vcpu_pc(vcpu) = read_sysreg_el2(SYS_ELR);
vcpu->arch.ctxt.gp_regs.regs.pstate = read_sysreg_el2(SYS_SPSR);
kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
write_sysreg_el2(vcpu->arch.ctxt.gp_regs.regs.pstate, SYS_SPSR);
write_sysreg_el2(*vcpu_pc(vcpu), SYS_ELR);
}
#endif /* __ARM64_KVM_EMULATE_H__ */
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