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091ebf07a2
This is a partial revert of 4cd8b5e2a1 "lguest: use KVM hypercalls";
we revert to using (just as questionable but more reliable) int $15 for
hypercalls. I didn't revert the register mapping, so we still use the
same calling convention as kvm.
KVM in more recent incarnations stopped injecting a fault when a guest
tried to use the VMCALL instruction from ring 1, so lguest under kvm
fails to make hypercalls. It was nice to share code with our KVM
cousins, but this was overreach.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Matias Zabaljauregui <zabaljauregui@gmail.com>
Cc: Avi Kivity <avi@redhat.com>
76 lines
2.6 KiB
C
76 lines
2.6 KiB
C
/* Architecture specific portion of the lguest hypercalls */
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#ifndef _ASM_X86_LGUEST_HCALL_H
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#define _ASM_X86_LGUEST_HCALL_H
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#define LHCALL_FLUSH_ASYNC 0
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#define LHCALL_LGUEST_INIT 1
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#define LHCALL_SHUTDOWN 2
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#define LHCALL_NEW_PGTABLE 4
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#define LHCALL_FLUSH_TLB 5
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#define LHCALL_LOAD_IDT_ENTRY 6
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#define LHCALL_SET_STACK 7
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#define LHCALL_TS 8
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#define LHCALL_SET_CLOCKEVENT 9
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#define LHCALL_HALT 10
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#define LHCALL_SET_PMD 13
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#define LHCALL_SET_PTE 14
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#define LHCALL_SET_PGD 15
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#define LHCALL_LOAD_TLS 16
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#define LHCALL_NOTIFY 17
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#define LHCALL_LOAD_GDT_ENTRY 18
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#define LHCALL_SEND_INTERRUPTS 19
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#define LGUEST_TRAP_ENTRY 0x1F
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/* Argument number 3 to LHCALL_LGUEST_SHUTDOWN */
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#define LGUEST_SHUTDOWN_POWEROFF 1
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#define LGUEST_SHUTDOWN_RESTART 2
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#ifndef __ASSEMBLY__
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#include <asm/hw_irq.h>
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/*G:030
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* But first, how does our Guest contact the Host to ask for privileged
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* operations? There are two ways: the direct way is to make a "hypercall",
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* to make requests of the Host Itself.
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*
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* Our hypercall mechanism uses the highest unused trap code (traps 32 and
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* above are used by real hardware interrupts). Seventeen hypercalls are
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* available: the hypercall number is put in the %eax register, and the
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* arguments (when required) are placed in %ebx, %ecx, %edx and %esi.
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* If a return value makes sense, it's returned in %eax.
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*
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* Grossly invalid calls result in Sudden Death at the hands of the vengeful
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* Host, rather than returning failure. This reflects Winston Churchill's
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* definition of a gentleman: "someone who is only rude intentionally".
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*/
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static inline unsigned long
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hcall(unsigned long call,
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unsigned long arg1, unsigned long arg2, unsigned long arg3,
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unsigned long arg4)
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{
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/* "int" is the Intel instruction to trigger a trap. */
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asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
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/* The call in %eax (aka "a") might be overwritten */
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: "=a"(call)
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/* The arguments are in %eax, %ebx, %ecx, %edx & %esi */
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: "a"(call), "b"(arg1), "c"(arg2), "d"(arg3), "S"(arg4)
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/* "memory" means this might write somewhere in memory.
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* This isn't true for all calls, but it's safe to tell
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* gcc that it might happen so it doesn't get clever. */
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: "memory");
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return call;
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}
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/* Can't use our min() macro here: needs to be a constant */
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#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
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#define LHCALL_RING_SIZE 64
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struct hcall_args {
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/* These map directly onto eax/ebx/ecx/edx/esi in struct lguest_regs */
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unsigned long arg0, arg1, arg2, arg3, arg4;
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};
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_LGUEST_HCALL_H */
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