Commit 5ae78e95 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: x86: Add dedicated emulator helpers for querying CPUID features 



Add feature-specific helpers for querying guest CPUID support from the
emulator instead of having the emulator do a full CPUID and perform its
own bit tests.  The primary motivation is to eliminate the emulator's
usage of bit() so that future patches can add more extensive build-time
assertions on the usage of bit() without having to expose yet more code
to the emulator.

Note, providing a generic guest_cpuid_has() to the emulator doesn't work
due to the existing built-time assertions in guest_cpuid_has(), which
require the feature being checked to be a compile-time constant.

No functional change intended.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 345599f9

arch/x86/include/asm/kvm_emulate.h

+4 −0
Original line number Diff line number Diff line
@@ -222,6 +222,10 @@ struct x86_emulate_ops { 


	bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx,

			  u32 *ecx, u32 *edx, bool check_limit);

	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);



	void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);



	unsigned (*get_hflags)(struct x86_emulate_ctxt *ctxt);

arch/x86/kvm/emulate.c

+3 −18
Original line number Diff line number Diff line
@@ -2348,12 +2348,7 @@ static int em_lseg(struct x86_emulate_ctxt *ctxt) 
static int emulator_has_longmode(struct x86_emulate_ctxt *ctxt)

{

#ifdef CONFIG_X86_64

	u32 eax, ebx, ecx, edx;



	eax = 0x80000001;

	ecx = 0;

	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);

	return edx & bit(X86_FEATURE_LM);

	return ctxt->ops->guest_has_long_mode(ctxt);

#else

	return false;

#endif
@@ -3618,18 +3613,11 @@ static int em_mov(struct x86_emulate_ctxt *ctxt) 
	return X86EMUL_CONTINUE;

}



#define FFL(x) bit(X86_FEATURE_##x)



static int em_movbe(struct x86_emulate_ctxt *ctxt)

{

	u32 ebx, ecx, edx, eax = 1;

	u16 tmp;



	/*

	 * Check MOVBE is set in the guest-visible CPUID leaf.

	 */

	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);

	if (!(ecx & FFL(MOVBE)))

	if (!ctxt->ops->guest_has_movbe(ctxt))

		return emulate_ud(ctxt);



	switch (ctxt->op_bytes) {
@@ -4027,10 +4015,7 @@ static int em_movsxd(struct x86_emulate_ctxt *ctxt) 


static int check_fxsr(struct x86_emulate_ctxt *ctxt)

{

	u32 eax = 1, ebx, ecx = 0, edx;



	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);

	if (!(edx & FFL(FXSR)))

	if (!ctxt->ops->guest_has_fxsr(ctxt))

		return emulate_ud(ctxt);



	if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))

arch/x86/kvm/x86.c

+18 −0
Original line number Diff line number Diff line
@@ -6245,6 +6245,21 @@ static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt, 
	return kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx, check_limit);

}



static bool emulator_guest_has_long_mode(struct x86_emulate_ctxt *ctxt)

{

	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_LM);

}



static bool emulator_guest_has_movbe(struct x86_emulate_ctxt *ctxt)

{

	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_MOVBE);

}



static bool emulator_guest_has_fxsr(struct x86_emulate_ctxt *ctxt)

{

	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_FXSR);

}



static ulong emulator_read_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg)

{

	return kvm_register_read(emul_to_vcpu(ctxt), reg);
@@ -6322,6 +6337,9 @@ static const struct x86_emulate_ops emulate_ops = { 
	.fix_hypercall       = emulator_fix_hypercall,

	.intercept           = emulator_intercept,

	.get_cpuid           = emulator_get_cpuid,

	.guest_has_long_mode = emulator_guest_has_long_mode,

	.guest_has_movbe     = emulator_guest_has_movbe,

	.guest_has_fxsr      = emulator_guest_has_fxsr,

	.set_nmi_mask        = emulator_set_nmi_mask,

	.get_hflags          = emulator_get_hflags,

	.set_hflags          = emulator_set_hflags,