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KVM: x86 emulator: reject SYSENTER in compatibility mode on AMD guests

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If the guest thinks it's an AMD, it will not have prepared the SYSENTER MSRs,
and if the guest executes SYSENTER in compatibility mode, it will fails.

Detect this condition and #UD instead, like the spec says.

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2012-02-01 12:23:21 +02:00
parent a52315e1d5
commit 1a18a69b76
1 changed files with 19 additions and 0 deletions
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19
arch/x86/kvm/emulate.c
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@ -1892,6 +1892,17 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,
ss->p = 1;
}
static bool vendor_intel(struct x86_emulate_ctxt *ctxt)
{
u32 eax, ebx, ecx, edx;
eax = ecx = 0;
return ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx)
&& ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx
&& ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx
&& edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx;
}
static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt)
{
struct x86_emulate_ops *ops = ctxt->ops;
@ -2008,6 +2019,14 @@ static int em_sysenter(struct x86_emulate_ctxt *ctxt)
if (ctxt->mode == X86EMUL_MODE_REAL)
return emulate_gp(ctxt, 0);
/*
* Not recognized on AMD in compat mode (but is recognized in legacy
* mode).
*/
if ((ctxt->mode == X86EMUL_MODE_PROT32) && (efer & EFER_LMA)
&& !vendor_intel(ctxt))
return emulate_ud(ctxt);
/* XXX sysenter/sysexit have not been tested in 64bit mode.
* Therefore, we inject an #UD.
*/