Cache the vendor CPU type in a global variable so that multiple calls to is_intel_cpu() do not need to re-execute CPUID.
Add cpu vendor check in kvm_hypercall() so that it executes correct vmcall/vmmcall instruction when running on Intel/AMD hosts. This avoids exit to KVM which anyway tries to patch the instruction according to the cpu type.
As part of this change, sync the global variable is_cpu_amd into the guest so the guest can determine which hypercall instruction to use without needing to re-execute CPUID for every hypercall.
Suggested-by: Sean Christopherson seanjc@google.com Signed-off-by: Vishal Annapurve vannapurve@google.com --- .../testing/selftests/kvm/lib/x86_64/processor.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c index 25ae972f5c71..c0ae938772f6 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c @@ -19,6 +19,7 @@ #define MAX_NR_CPUID_ENTRIES 100
vm_vaddr_t exception_handlers; +static bool is_cpu_amd;
static void regs_dump(FILE *stream, struct kvm_regs *regs, uint8_t indent) { @@ -1019,7 +1020,7 @@ static bool cpu_vendor_string_is(const char *vendor)
bool is_intel_cpu(void) { - return cpu_vendor_string_is("GenuineIntel"); + return (is_cpu_amd == false); }
/* @@ -1027,7 +1028,7 @@ bool is_intel_cpu(void) */ bool is_amd_cpu(void) { - return cpu_vendor_string_is("AuthenticAMD"); + return (is_cpu_amd == true); }
void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits) @@ -1182,9 +1183,15 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2, { uint64_t r;
- asm volatile("vmcall" + if (is_amd_cpu()) + asm volatile("vmmcall" : "=a"(r) : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3)); + else + asm volatile("vmcall" + : "=a"(r) + : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3)); + return r; }
@@ -1314,8 +1321,10 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm)
void kvm_selftest_arch_init(void) { + is_cpu_amd = cpu_vendor_string_is("AuthenticAMD"); }
void kvm_arch_post_vm_elf_load(struct kvm_vm *vm) { + sync_global_to_guest(vm, is_cpu_amd); }