diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2022-10-22 04:17:53 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-18 11:45:00 +0100 |
commit | 196c6f0c3e217223c060f5376f1095948df33781 (patch) | |
tree | a5b775e749f8f072bf098ea8fd1098662211eaab /arch | |
parent | 0027164b24f252d54d6d5b8e718b7d782859713a (diff) |
KVM: x86: Do not return host topology information from KVM_GET_SUPPORTED_CPUID
[ Upstream commit 45e966fcca03ecdcccac7cb236e16eea38cc18af ]
Passing the host topology to the guest is almost certainly wrong
and will confuse the scheduler. In addition, several fields of
these CPUID leaves vary on each processor; it is simply impossible to
return the right values from KVM_GET_SUPPORTED_CPUID in such a way that
they can be passed to KVM_SET_CPUID2.
The values that will most likely prevent confusion are all zeroes.
Userspace will have to override it anyway if it wishes to present a
specific topology to the guest.
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kvm/cpuid.c | 32 |
1 files changed, 16 insertions, 16 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 06a776fdb90c..de4b171cb76b 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -511,16 +511,22 @@ struct kvm_cpuid_array { int nent; }; +static struct kvm_cpuid_entry2 *get_next_cpuid(struct kvm_cpuid_array *array) +{ + if (array->nent >= array->maxnent) + return NULL; + + return &array->entries[array->nent++]; +} + static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array, u32 function, u32 index) { - struct kvm_cpuid_entry2 *entry; + struct kvm_cpuid_entry2 *entry = get_next_cpuid(array); - if (array->nent >= array->maxnent) + if (!entry) return NULL; - entry = &array->entries[array->nent++]; - entry->function = function; entry->index = index; entry->flags = 0; @@ -698,22 +704,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->edx = edx.full; break; } - /* - * Per Intel's SDM, the 0x1f is a superset of 0xb, - * thus they can be handled by common code. - */ case 0x1f: case 0xb: /* - * Populate entries until the level type (ECX[15:8]) of the - * previous entry is zero. Note, CPUID EAX.{0x1f,0xb}.0 is - * the starting entry, filled by the primary do_host_cpuid(). + * No topology; a valid topology is indicated by the presence + * of subleaf 1. */ - for (i = 1; entry->ecx & 0xff00; ++i) { - entry = do_host_cpuid(array, function, i); - if (!entry) - goto out; - } + entry->eax = entry->ebx = entry->ecx = 0; break; case 0xd: entry->eax &= supported_xcr0; @@ -866,6 +863,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->ebx = entry->ecx = entry->edx = 0; break; case 0x8000001e: + /* Do not return host topology information. */ + entry->eax = entry->ebx = entry->ecx = 0; + entry->edx = 0; /* reserved */ break; /* Support memory encryption cpuid if host supports it */ case 0x8000001F: |