Currently when kvm_update_cpuid_runtime() runs, it assumes that the
KVM_CPUID_FEATURES leaf is located at 0x40000001. This is not true,
however, if Hyper-V support is enabled. In this case the KVM leaves will
be offset.
This patch introdues as new 'kvm_cpuid_base' field into struct
kvm_vcpu_arch to track the location of the KVM leaves and function
kvm_update_kvm_cpuid_base() (called from kvm_set_cpuid()) to locate the
leaves using the 'KVMKVMKVM\0\0\0' signature (which is now given a
definition in kvm_para.h). Adjustment of KVM_CPUID_FEATURES will hence now
target the correct leaf.
NOTE: A new for_each_possible_hypervisor_cpuid_base() macro is intoduced
into processor.h to avoid having duplicate code for the iteration
over possible hypervisor base leaves.
Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Cc: Wanpeng Li <wanpengli@xxxxxxxxxxx>
Cc: Jim Mattson <jmattson@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
v2:
- Added new for_each_possible_hypervisor_cpuid_base() macro
- Added KVM_SIGNATURE definition
- Other amendments as requested by Sean
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/include/asm/processor.h | 5 ++-
arch/x86/include/uapi/asm/kvm_para.h | 1 +
arch/x86/kernel/kvm.c | 2 +-
arch/x86/kvm/cpuid.c | 46 ++++++++++++++++++++++++----
5 files changed, 47 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 88fce6ab4bbd..21133ffa23e9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -725,6 +725,7 @@ struct kvm_vcpu_arch {
int cpuid_nent;
struct kvm_cpuid_entry2 *cpuid_entries;
+ u32 kvm_cpuid_base;
u64 reserved_gpa_bits;
int maxphyaddr;
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9ad2acaaae9b..726318cda082 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -807,11 +807,14 @@ static inline u32 amd_get_nodes_per_socket(void) { return 0; }
static inline u32 amd_get_highest_perf(void) { return 0; }
#endif
+#define for_each_possible_hypervisor_cpuid_base(function) \
+ for (function = 0x40000000; function < 0x40010000; function += 0x100)
+
static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
{
uint32_t base, eax, signature[3];
- for (base = 0x40000000; base < 0x40010000; base += 0x100) {
+ for_each_possible_hypervisor_cpuid_base(base) {
cpuid(base, &eax, &signature[0], &signature[1], &signature[2]);
if (!memcmp(sig, signature, 12) &&
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 5146bbab84d4..6e64b27b2c1e 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -8,6 +8,7 @@
* should be used to determine that a VM is running under KVM.
*/
#define KVM_CPUID_SIGNATURE 0x40000000
+#define KVM_SIGNATURE "KVMKVMKVM\0\0\0"
/* This CPUID returns two feature bitmaps in eax, edx. Before enabling
* a particular paravirtualization, the appropriate feature bit should
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index b656456c3a94..c97859170286 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -755,7 +755,7 @@ static noinline uint32_t __kvm_cpuid_base(void)
return 0; /* So we don't blow up on old processors */
if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
- return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
+ return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
return 0;
}
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 41529c168e91..e19dabf1848b 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -99,11 +99,45 @@ static int kvm_check_cpuid(struct kvm_cpuid_entry2 *entries, int nent)
return 0;
}
-void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
+static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
{
- struct kvm_cpuid_entry2 *best;
+ u32 function;
+ struct kvm_cpuid_entry2 *entry;
+
+ vcpu->arch.kvm_cpuid_base = 0;
+
+ for_each_possible_hypervisor_cpuid_base(function) {
+ entry = kvm_find_cpuid_entry(vcpu, function, 0);
+
+ if (entry) {
+ u32 signature[3];
+
+ signature[0] = entry->ebx;
+ 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;
+ break;
+ }
+ }
+ }
+}
+
+struct kvm_cpuid_entry2 *kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu)
+{
+ u32 base = vcpu->arch.kvm_cpuid_base;
+
+ if (!base)
+ return NULL;
+
+ return kvm_find_cpuid_entry(vcpu, base | KVM_CPUID_FEATURES, 0);
+}
- best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
+void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *best = kvm_find_kvm_cpuid_features(vcpu);
/*
* save the feature bitmap to avoid cpuid lookup for every PV
@@ -142,7 +176,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
- best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
+ best = kvm_find_kvm_cpuid_features(vcpu);
if (kvm_hlt_in_guest(vcpu->kvm) && best &&
(best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);
@@ -252,6 +286,7 @@ 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_cpuid_runtime(vcpu);
kvm_vcpu_after_set_cpuid(vcpu);
@@ -872,8 +907,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
}
break;
case KVM_CPUID_SIGNATURE: {
- static const char signature[12] = "KVMKVMKVM\0\0";
- const u32 *sigptr = (const u32 *)signature;
+ const u32 *sigptr = (const u32 *)KVM_SIGNATURE;
entry->eax = KVM_CPUID_FEATURES;
entry->ebx = sigptr[0];
entry->ecx = sigptr[1];
--
2.20.1
