diff options
| author | Alexander Potapenko <glider@google.com> | 2026-02-05 13:59:18 +0100 |
|---|---|---|
| committer | Alexander Potapenko <glider@google.com> | 2026-02-09 09:43:36 +0000 |
| commit | 168b436f204a8cae6542d42542e18cc1197ac5b2 (patch) | |
| tree | 6692e6d1adf4770d717b4551f19a22b9be4ec0ff /executor | |
| parent | 91d686647eca17c731c837e1f1b817e8a61ddb6a (diff) | |
executor: enable X86_EFER_SVME for AMD
When setting up L1 guest, execute CPUID and enable X86_EFER_SVME for
AMD CPUs.
Diffstat (limited to 'executor')
| -rw-r--r-- | executor/common_kvm_amd64.h | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/executor/common_kvm_amd64.h b/executor/common_kvm_amd64.h index d090afaa0..474bc875b 100644 --- a/executor/common_kvm_amd64.h +++ b/executor/common_kvm_amd64.h @@ -436,9 +436,17 @@ static void setup_gdt_64(struct gdt_entry* gdt) // We'll keep the base 0 for simplicity, so the second entry (index 4) can remain 0. } +static void get_cpuid(uint32 eax, uint32 ecx, uint32* a, uint32* b, uint32* c, uint32* d) +{ + *a = *b = *c = *d = 0; + asm volatile("cpuid" + : "=a"(*a), "=b"(*b), "=c"(*c), "=d"(*d) + : "a"(eax), "c"(ecx)); +} + // This only sets up a 64-bit VCPU. // TODO: Should add support for other modes. -static void setup_gdt_ldt_pg(struct kvm_syz_vm* vm, int cpufd) +static void setup_gdt_ldt_pg(struct kvm_syz_vm* vm, int cpufd, int cpu_id) { struct kvm_sregs sregs; ioctl(cpufd, KVM_GET_SREGS, &sregs); @@ -507,6 +515,17 @@ static void setup_gdt_ldt_pg(struct kvm_syz_vm* vm, int cpufd) sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG; sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR; sregs.efer |= (X86_EFER_LME | X86_EFER_LMA | X86_EFER_NXE); + + uint32 eax = 0, ebx = 0, ecx = 0, edx = 0; + get_cpuid(0, 0, &eax, &ebx, &ecx, &edx); + if (ebx == 0x68747541 && edx == 0x69746e65 && ecx == 0x444d4163) { // "AuthenticAMD" + sregs.efer |= X86_EFER_SVME; + + // Zero out the HSAVE area for AMD. + void* hsave_host = (void*)((uint64)vm->host_mem + X86_SYZOS_ADDR_VM_ARCH_SPECIFIC(cpu_id)); + memset(hsave_host, 0, KVM_PAGE_SIZE); + } + sregs.cr3 = X86_ADDR_PML4; ioctl(cpufd, KVM_SET_SREGS, &sregs); @@ -1105,7 +1124,7 @@ static void install_user_code(struct kvm_syz_vm* vm, int cpufd, int cpu_id, cons text_size = KVM_PAGE_SIZE; void* target = (void*)((uint64)vm->user_text + (KVM_PAGE_SIZE * cpu_id)); memcpy(target, text, text_size); - setup_gdt_ldt_pg(vm, cpufd); + setup_gdt_ldt_pg(vm, cpufd, cpu_id); setup_cpuid(cpufd); reset_cpu_regs(cpufd, cpu_id, text_size); } |