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KVM: x86: Make sure KVM_CPUID_FEATURES really are KVM_CPUID_FEATURES

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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@amazon.com>
Message-Id: <20211105095101.5384-3-pdurrant@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paul Durrant
2021-11-05 09:51:01 +00:00
committed by Paolo Bonzini
parent 8b44b174f6
commit 760849b147
5 changed files with 47 additions and 8 deletions
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5
arch/x86/include/asm/processor.h
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@@ -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) &&