On Mon, 22 Jul 2024 10:18:59 +0000 "manish.mishra" <manish.mis...@nutanix.com> wrote:
> QEMU does not set 0x1f in case VM does not have extended CPU topology > and expects guests to fallback to 0xb. Some versions of windows i.e. > windows 10, 11 does not like this behavior and expects this leaf to be ^^^^^^^^^^^^^ be more clear about > populated. This is observed with windows VMs with secure boot, uefi > and HyperV role enabled. add here exact QME CLI and necessary guest OS details to reproduce the issue. > Leaf 0x1f is superset of 0xb, so it makes sense to set 0x1f equivalent > to 0xb by default and workaround windows issue. This change adds a > new property 'cpuid-0x1f-enforce' to set leaf 0x1f equivalent to 0xb in > case extended CPU topology is not present and behave as before otherwise. > --- maybe instead of adding workaround it would be better to enable 1F leaf on CPU models that supposed to have it? > hw/i386/pc.c | 1 + > target/i386/cpu.c | 71 +++++++++++++++++++++++++++---------------- > target/i386/cpu.h | 5 +++ > target/i386/kvm/kvm.c | 4 ++- > 4 files changed, 53 insertions(+), 28 deletions(-) > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index c74931d577..4cab04e443 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -85,6 +85,7 @@ GlobalProperty pc_compat_9_0[] = { > { TYPE_X86_CPU, "guest-phys-bits", "0" }, > { "sev-guest", "legacy-vm-type", "on" }, > { TYPE_X86_CPU, "legacy-multi-node", "on" }, > + { TYPE_X86_CPU, "cpuid-0x1f-enforce", "false" }, > }; > const size_t pc_compat_9_0_len = G_N_ELEMENTS(pc_compat_9_0); > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index 4688d140c2..f89b2ef335 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -416,6 +416,43 @@ static void encode_topo_cpuid1f(CPUX86State *env, > uint32_t count, > assert(!(*eax & ~0x1f)); > } > > +static void encode_topo_cpuid_b(CPUX86State *env, uint32_t count, > + X86CPUTopoInfo *topo_info, > + uint32_t threads_per_pkg, > + uint32_t *eax, uint32_t *ebx, > + uint32_t *ecx, uint32_t *edx) > +{ > + X86CPU *cpu = env_archcpu(env); > + > + if (!cpu->enable_cpuid_0xb) { > + *eax = *ebx = *ecx = *edx = 0; > + return; > + } > + > + *ecx = count & 0xff; > + *edx = cpu->apic_id; > + > + switch (count) { > + case 0: > + *eax = apicid_core_offset(topo_info); > + *ebx = topo_info->threads_per_core; > + *ecx |= CPUID_B_ECX_TOPO_LEVEL_SMT << 8; > + break; > + case 1: > + *eax = apicid_pkg_offset(topo_info); > + *ebx = threads_per_pkg; > + *ecx |= CPUID_B_ECX_TOPO_LEVEL_CORE << 8; > + break; > + default: > + *eax = 0; > + *ebx = 0; > + *ecx |= CPUID_B_ECX_TOPO_LEVEL_INVALID << 8; > + } > + > + assert(!(*eax & ~0x1f)); > + *ebx &= 0xffff; /* The count doesn't need to be reliable. */ > +} > + > /* Encode cache info for CPUID[0x80000005].ECX or CPUID[0x80000005].EDX */ > static uint32_t encode_cache_cpuid80000005(CPUCacheInfo *cache) > { > @@ -6601,33 +6638,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, > uint32_t count, > break; > case 0xB: > /* Extended Topology Enumeration Leaf */ > - if (!cpu->enable_cpuid_0xb) { > - *eax = *ebx = *ecx = *edx = 0; > - break; > - } > - > - *ecx = count & 0xff; > - *edx = cpu->apic_id; > - > - switch (count) { > - case 0: > - *eax = apicid_core_offset(&topo_info); > - *ebx = topo_info.threads_per_core; > - *ecx |= CPUID_B_ECX_TOPO_LEVEL_SMT << 8; > - break; > - case 1: > - *eax = apicid_pkg_offset(&topo_info); > - *ebx = threads_per_pkg; > - *ecx |= CPUID_B_ECX_TOPO_LEVEL_CORE << 8; > - break; > - default: > - *eax = 0; > - *ebx = 0; > - *ecx |= CPUID_B_ECX_TOPO_LEVEL_INVALID << 8; > - } > - > - assert(!(*eax & ~0x1f)); > - *ebx &= 0xffff; /* The count doesn't need to be reliable. */ > + encode_topo_cpuid_b(env, count, &topo_info, threads_per_pkg, > + eax, ebx, ecx, edx); > break; > case 0x1C: > if (cpu->enable_pmu && (env->features[FEAT_7_0_EDX] & > CPUID_7_0_EDX_ARCH_LBR)) { > @@ -6639,6 +6651,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, > uint32_t count, > /* V2 Extended Topology Enumeration Leaf */ > if (!x86_has_extended_topo(env->avail_cpu_topo)) { > *eax = *ebx = *ecx = *edx = 0; > + if (cpu->enable_cpuid_0x1f_enforce) { > + encode_topo_cpuid_b(env, count, &topo_info, threads_per_pkg, > + eax, ebx, ecx, edx); > + } > break; > } > > @@ -8316,6 +8332,7 @@ static Property x86_cpu_properties[] = { > DEFINE_PROP_BOOL("full-cpuid-auto-level", X86CPU, full_cpuid_auto_level, > true), > DEFINE_PROP_STRING("hv-vendor-id", X86CPU, hyperv_vendor), > DEFINE_PROP_BOOL("cpuid-0xb", X86CPU, enable_cpuid_0xb, true), > + DEFINE_PROP_BOOL("cpuid-0x1f-enforce", X86CPU, > enable_cpuid_0x1f_enforce, true), > DEFINE_PROP_BOOL("x-vendor-cpuid-only", X86CPU, vendor_cpuid_only, true), > DEFINE_PROP_BOOL("x-amd-topoext-features-only", X86CPU, > amd_topoext_features_only, true), > DEFINE_PROP_BOOL("lmce", X86CPU, enable_lmce, false), > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index 1e121acef5..718b9f2b0b 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -2102,6 +2102,11 @@ struct ArchCPU { > /* Compatibility bits for old machine types: */ > bool enable_cpuid_0xb; > > + /* Always return values for 0x1f leaf. In cases where extended CPU > topology > + * is not supported, return values equivalent of leaf 0xb. > + */ > + bool enable_cpuid_0x1f_enforce; > + > /* Enable auto level-increase for all CPUID leaves */ > bool full_cpuid_auto_level; > > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index becca2efa5..a9c6f02900 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -1799,6 +1799,7 @@ static uint32_t kvm_x86_build_cpuid(CPUX86State *env, > uint32_t limit, i, j; > uint32_t unused; > struct kvm_cpuid_entry2 *c; > + X86CPU *cpu = env_archcpu(env); > > cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused); > > @@ -1831,7 +1832,8 @@ static uint32_t kvm_x86_build_cpuid(CPUX86State *env, > break; > } > case 0x1f: > - if (!x86_has_extended_topo(env->avail_cpu_topo)) { > + if (!x86_has_extended_topo(env->avail_cpu_topo) && > + !cpu->enable_cpuid_0x1f_enforce) { > cpuid_i--; > break; > }