[PATCH v19 129/130] RFC: KVM: x86: Add x86 callback to check cpuid

isaku.yamahata
2024-02-26T08:29:21Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

The x86 backend should check the consistency of KVM_SET_CPUID2 because it
has its constraint. Add a callback for it. The backend code will come as
another patch.

Suggested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/lkml/ZDiGpCkXOcCm074O@google.com/
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 2 ++
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/cpuid.c | 20 ++++++++++++--------
3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 85c04aad6ab3..3a7140129855 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -20,6 +20,8 @@ KVM_X86_OP(hardware_disable)
KVM_X86_OP(hardware_unsetup)
KVM_X86_OP_OPTIONAL_RET0(offline_cpu)
KVM_X86_OP(has_emulated_msr)
+/* TODO: Once all backend implemented this op, remove _OPTIONAL_RET0. */
+KVM_X86_OP_OPTIONAL_RET0(vcpu_check_cpuid)
KVM_X86_OP(vcpu_after_set_cpuid)
KVM_X86_OP(is_vm_type_supported)
KVM_X86_OP_OPTIONAL(max_vcpus);
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 920fb771246b..e4d40e31fc31 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1638,6 +1638,7 @@ struct kvm_x86_ops {
void (*hardware_unsetup)(void);
int (*offline_cpu)(void);
bool (*has_emulated_msr)(struct kvm *kvm, u32 index);
+ int (*vcpu_check_cpuid)(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, int nent);
void (*vcpu_after_set_cpuid)(struct kvm_vcpu *vcpu);

bool (*is_vm_type_supported)(unsigned long vm_type);
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8cdcd6f406aa..b57006943247 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -136,6 +136,7 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu,
{
struct kvm_cpuid_entry2 *best;
u64 xfeatures;
+ int r;

/*
* The existing code assumes virtual address is 48-bit or 57-bit in the
@@ -155,15 +156,18 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu,
* enabling in the FPU, e.g. to expand the guest XSAVE state size.
*/
best = cpuid_entry2_find(entries, nent, 0xd, 0);
- if (!best)
- return 0;
-
- xfeatures = best->eax | ((u64)best->edx << 32);
- xfeatures &= XFEATURE_MASK_USER_DYNAMIC;
- if (!xfeatures)
- return 0;
+ if (best) {
+ xfeatures = best->eax | ((u64)best->edx << 32);
+ xfeatures &= XFEATURE_MASK_USER_DYNAMIC;
+ if (xfeatures) {
+ r = fpu_enable_guest_xfd_features(&vcpu->arch.guest_fpu,
+ xfeatures);
+ if (r)
+ return r;
+ }
+ }

- return fpu_enable_guest_xfd_features(&vcpu->arch.guest_fpu, xfeatures);
+ return static_call(kvm_x86_vcpu_check_cpuid)(vcpu, entries, nent);
}

/* Check whether the supplied CPUID data is equal to what is already set for the vCPU. */
--
2.25.1