[PATCH v2 1/1] x86/kvm/fpu: Remove kvm_vcpu_arch.guest_supported_xcr0

[Leonardo Bras]

kvm_vcpu_arch currently contains the guest supported features in both
guest_supported_xcr0 and guest_fpu.fpstate->user_xfeatures field.

Currently both fields are set to the same value in
kvm_vcpu_after_set_cpuid() and are not changed anywhere else after that.

Since it's not good to keep duplicated data, remove guest_supported_xcr0.

To keep the code more readable, introduce kvm_guest_supported_xcr()
and kvm_guest_supported_xfd() to replace the previous usages of
guest_supported_xcr0.

Signed-off-by: Leonardo Bras <leobras@xxxxxxxxxx>
Message-Id: <20220217053028.96432-3-leobras@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
This patch includes a fix from a bug found by "kernel test robot",
regarding compilation of non-x86_64 builds.

 arch/x86/include/asm/kvm_host.h |  1 -
 arch/x86/kvm/cpuid.c            |  5 +++--
 arch/x86/kvm/x86.c              | 20 +++++++++++++++-----
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6dcccb304775..ec9830d2aabf 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -703,7 +703,6 @@ struct kvm_vcpu_arch {
 	struct fpu_guest guest_fpu;
 
 	u64 xcr0;
-	u64 guest_supported_xcr0;
 
 	struct kvm_pio_request pio;
 	void *pio_data;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 71125291c578..b8f8d268d058 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -282,6 +282,7 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	struct kvm_cpuid_entry2 *best;
+	u64 guest_supported_xcr0;
 
 	best = kvm_find_cpuid_entry(vcpu, 1, 0);
 	if (best && apic) {
@@ -293,10 +294,10 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 		kvm_apic_set_version(vcpu);
 	}
 
-	vcpu->arch.guest_supported_xcr0 =
+	guest_supported_xcr0 =
 		cpuid_get_supported_xcr0(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent);
 
-	vcpu->arch.guest_fpu.fpstate->user_xfeatures = vcpu->arch.guest_supported_xcr0;
+	vcpu->arch.guest_fpu.fpstate->user_xfeatures = guest_supported_xcr0;
 
 	kvm_update_pv_runtime(vcpu);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 641044db415d..ca0fae020961 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -984,6 +984,18 @@ void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_load_host_xsave_state);
 
+static inline u64 kvm_guest_supported_xcr0(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.guest_fpu.fpstate->user_xfeatures;
+}
+
+#ifdef CONFIG_X86_64
+static inline u64 kvm_guest_supported_xfd(struct kvm_vcpu *vcpu)
+{
+	return kvm_guest_supported_xcr0(vcpu) & XFEATURE_MASK_USER_DYNAMIC;
+}
+#endif
+
 static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
 	u64 xcr0 = xcr;
@@ -1003,7 +1015,7 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 	 * saving.  However, xcr0 bit 0 is always set, even if the
 	 * emulated CPU does not support XSAVE (see kvm_vcpu_reset()).
 	 */
-	valid_bits = vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FP;
+	valid_bits = kvm_guest_supported_xcr0(vcpu) | XFEATURE_MASK_FP;
 	if (xcr0 & ~valid_bits)
 		return 1;
 
@@ -3706,8 +3718,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		    !guest_cpuid_has(vcpu, X86_FEATURE_XFD))
 			return 1;
 
-		if (data & ~(XFEATURE_MASK_USER_DYNAMIC &
-			     vcpu->arch.guest_supported_xcr0))
+		if (data & ~kvm_guest_supported_xfd(vcpu))
 			return 1;
 
 		fpu_update_guest_xfd(&vcpu->arch.guest_fpu, data);
@@ -3717,8 +3728,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		    !guest_cpuid_has(vcpu, X86_FEATURE_XFD))
 			return 1;
 
-		if (data & ~(XFEATURE_MASK_USER_DYNAMIC &
-			     vcpu->arch.guest_supported_xcr0))
+		if (data & ~kvm_guest_supported_xfd(vcpu))
 			return 1;
 
 		vcpu->arch.guest_fpu.xfd_err = data;
-- 
2.35.1