From 4067c2395e80e5109b485f1928a797be17d758ae Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 5 Apr 2024 16:56:01 -0700 Subject: [PATCH] KVM: x86: Allow SYSENTER in Compatibility Mode for all Intel compat vCPUs Emulate SYSENTER in Compatibility Mode for all vCPUs models that are compatible with Intel's architecture, as the behavior if SYSENTER is architecturally defined in Intel's SDM, i.e. should be followed by any CPU that implements Intel's architecture. Link: https://lore.kernel.org/r/20240405235603.1173076-9-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/emulate.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 1fb73d96bdf0c..26e8c197a1d16 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2354,6 +2354,7 @@ 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; @@ -2362,6 +2363,7 @@ static bool vendor_intel(struct x86_emulate_ctxt *ctxt) 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) { @@ -2444,11 +2446,11 @@ static int em_sysenter(struct x86_emulate_ctxt *ctxt) return emulate_gp(ctxt, 0); /* - * Not recognized on AMD in compat mode (but is recognized in legacy - * mode). + * Intel's architecture allows SYSENTER in compatibility mode, but AMD + * does not. Note, AMD does allow SYSENTER in legacy protected mode. */ - if ((ctxt->mode != X86EMUL_MODE_PROT64) && (efer & EFER_LMA) - && !vendor_intel(ctxt)) + if ((ctxt->mode != X86EMUL_MODE_PROT64) && (efer & EFER_LMA) && + !ctxt->ops->guest_cpuid_is_intel_compatible(ctxt)) return emulate_ud(ctxt); /* sysenter/sysexit have not been tested in 64bit mode. */