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KVM: x86: Open code vendor_intel() in string_registers_quirk()

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Open code the is_guest_vendor_intel() check in string_registers_quirk() to
discourage makiking exact vendor==Intel checks in the emulator, and to
remove the rather awful #ifdeffery.

The string quirk is literally the only Intel specific, *non-architectural*
behavior that KVM emulates.  All Intel specific behavior that is
architecturally defined applies to all vendors that are compatible with
Intel's architecture, i.e. should use guest_cpuid_is_intel_compatible().

Link: https://lore.kernel.org/r/20240405235603.1173076-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-04-05 16:56:02 -07:00
parent 4067c2395e
commit bdaff4f92b
1 changed files with 8 additions and 12 deletions
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20
arch/x86/kvm/emulate.c
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@ -2354,17 +2354,6 @@ setup_syscalls_segments(struct desc_struct *cs, struct desc_struct *ss)
ss->avl = 0;
}
#ifdef CONFIG_X86_64
static bool vendor_intel(struct x86_emulate_ctxt *ctxt)
{
u32 eax, ebx, ecx, edx;
eax = ecx = 0;
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, true);
return is_guest_vendor_intel(ebx, ecx, edx);
}
#endif
static int em_syscall(struct x86_emulate_ctxt *ctxt)
{
const struct x86_emulate_ops *ops = ctxt->ops;
@ -2622,7 +2611,14 @@ static void string_registers_quirk(struct x86_emulate_ctxt *ctxt)
* manner when ECX is zero due to REP-string optimizations.
*/
#ifdef CONFIG_X86_64
if (ctxt->ad_bytes != 4 || !vendor_intel(ctxt))
u32 eax, ebx, ecx, edx;
if (ctxt->ad_bytes != 4)
return;
eax = ecx = 0;
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, true);
if (!is_guest_vendor_intel(ebx, ecx, edx))
return;
*reg_write(ctxt, VCPU_REGS_RCX) = 0;