On Wed, Mar 16, 2022 at 06:18:11AM +0800, Paolo Bonzini wrote:
> On 3/7/22 13:26, Hou Wenlong wrote:
> >When RDTSCP is supported but RDPID is not supported in host,
> >RDPID emulation is available. However, __kvm_get_msr() would
> >only fail when RDTSCP/RDPID both are disabled in guest, so
> >the emulator wouldn't inject a #UD when RDPID is disabled but
> >RDTSCP is enabled in guest.
> >
> >Fixes: fb6d4d340e05 ("KVM: x86: emulate RDPID")
> >Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
> >---
> > arch/x86/kvm/emulate.c | 4 +++-
> > arch/x86/kvm/kvm_emulate.h | 1 +
> > arch/x86/kvm/x86.c | 6 ++++++
> > 3 files changed, 10 insertions(+), 1 deletion(-)
> >
> >diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> >index 3497a35bd085..be83c9c8482d 100644
> >--- a/arch/x86/kvm/emulate.c
> >+++ b/arch/x86/kvm/emulate.c
> >@@ -3521,8 +3521,10 @@ static int em_rdpid(struct x86_emulate_ctxt *ctxt)
> > {
> > u64 tsc_aux = 0;
> >- if (ctxt->ops->get_msr(ctxt, MSR_TSC_AUX, &tsc_aux))
> >+ if (!ctxt->ops->guest_has_rdpid(ctxt))
> > return emulate_ud(ctxt);
> >+
> >+ ctxt->ops->get_msr(ctxt, MSR_TSC_AUX, &tsc_aux);
> > ctxt->dst.val = tsc_aux;
> > return X86EMUL_CONTINUE;
> > }
> >diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
> >index 29ac5a9679e5..1cbd46cf71f9 100644
> >--- a/arch/x86/kvm/kvm_emulate.h
> >+++ b/arch/x86/kvm/kvm_emulate.h
> >@@ -228,6 +228,7 @@ struct x86_emulate_ops {
> > bool (*guest_has_long_mode)(struct x86_emulate_ctxt *ctxt);
> > bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt);
> > bool (*guest_has_fxsr)(struct x86_emulate_ctxt *ctxt);
> >+ bool (*guest_has_rdpid)(struct x86_emulate_ctxt *ctxt);
> > void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);
> >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> >index 09c5677f4186..44f97038d3e5 100644
> >--- a/arch/x86/kvm/x86.c
> >+++ b/arch/x86/kvm/x86.c
> >@@ -7723,6 +7723,11 @@ static bool emulator_guest_has_fxsr(struct x86_emulate_ctxt *ctxt)
> > return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_FXSR);
> > }
> >+static bool emulator_guest_has_rdpid(struct x86_emulate_ctxt *ctxt)
> >+{
> >+ return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_RDPID);
> >+}
> >+
> > static ulong emulator_read_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg)
> > {
> > return kvm_register_read_raw(emul_to_vcpu(ctxt), reg);
> >@@ -7807,6 +7812,7 @@ static const struct x86_emulate_ops emulate_ops = {
> > .guest_has_long_mode = emulator_guest_has_long_mode,
> > .guest_has_movbe = emulator_guest_has_movbe,
> > .guest_has_fxsr = emulator_guest_has_fxsr,
> >+ .guest_has_rdpid = emulator_guest_has_rdpid,
> > .set_nmi_mask = emulator_set_nmi_mask,
> > .get_hflags = emulator_get_hflags,
> > .exiting_smm = emulator_exiting_smm,
>
> Queued, thanks.
>
> Would you try replacing the ->guest_has_... callbacks with just one
> that takes an X86_FEATURE_* constant as a second argument?
>
> Paolo
I've tried doing it before sending the patch, but the compilation failed
due to BUILD_BUG_ON in reverse_cpuid_check(), which requires a constant.
