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Subject[PATCH v6 1/2] KVM: x86/cpuid: generalize kvm_update_kvm_cpuid_base() and also capture limit
Date
A sunsequent patch will need to acquire the CPUID leaf range for emulated
Xen so explicitly pass the signature of the hypervisor we're interested in
to the new function. Also introduce a new kvm_hypervisor_cpuid structure
so we can neatly store both the base and limit leaf indices.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>

v6:
- New in this version
---
arch/x86/include/asm/kvm_host.h | 7 ++++++-
arch/x86/kvm/cpuid.c | 15 ++++++++-------
2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f35f1ff4427b..ff201ad35551 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -710,6 +710,11 @@ struct kvm_queued_exception {
bool has_payload;
};

+struct kvm_hypervisor_cpuid {
+ u32 base;
+ u32 limit;
+};
+
struct kvm_vcpu_arch {
/*
* rip and regs accesses must go through
@@ -826,7 +831,7 @@ struct kvm_vcpu_arch {

int cpuid_nent;
struct kvm_cpuid_entry2 *cpuid_entries;
- u32 kvm_cpuid_base;
+ struct kvm_hypervisor_cpuid kvm_cpuid;

u64 reserved_gpa_bits;
int maxphyaddr;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0b5bf013fcb8..2468720f8d84 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -180,12 +180,13 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
return 0;
}

-static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
+static void kvm_update_hypervisor_cpuid(struct kvm_vcpu *vcpu, const char *hypervisor_signature,
+ struct kvm_hypervisor_cpuid *hypervisor_cpuid)
{
u32 function;
struct kvm_cpuid_entry2 *entry;

- vcpu->arch.kvm_cpuid_base = 0;
+ memset(hypervisor_cpuid, 0, sizeof(*hypervisor_cpuid));

for_each_possible_hypervisor_cpuid_base(function) {
entry = kvm_find_cpuid_entry(vcpu, function);
@@ -197,9 +198,9 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
signature[1] = entry->ecx;
signature[2] = entry->edx;

- BUILD_BUG_ON(sizeof(signature) > sizeof(KVM_SIGNATURE));
- if (!memcmp(signature, KVM_SIGNATURE, sizeof(signature))) {
- vcpu->arch.kvm_cpuid_base = function;
+ if (!memcmp(signature, hypervisor_signature, sizeof(signature))) {
+ hypervisor_cpuid->base = function;
+ hypervisor_cpuid->limit = entry->eax;
break;
}
}
@@ -209,7 +210,7 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
static struct kvm_cpuid_entry2 *__kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu,
struct kvm_cpuid_entry2 *entries, int nent)
{
- u32 base = vcpu->arch.kvm_cpuid_base;
+ u32 base = vcpu->arch.kvm_cpuid.base;

if (!base)
return NULL;
@@ -439,7 +440,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
vcpu->arch.cpuid_entries = e2;
vcpu->arch.cpuid_nent = nent;

- kvm_update_kvm_cpuid_base(vcpu);
+ kvm_update_hypervisor_cpuid(vcpu, KVM_SIGNATURE, &vcpu->arch.kvm_cpuid);
kvm_vcpu_after_set_cpuid(vcpu);

return 0;
--
2.20.1
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