From: Sean Christopherson seanjc@google.com
commit 4bf48e3c0aafd32b960d341c4925b48f416f14a5 upstream.
Ignore the guest MAXPHYADDR reported by CPUID.0x8000_0008 if TDP, i.e. NPT, is disabled, and instead use the host's MAXPHYADDR. Per AMD'S APM:
Maximum guest physical address size in bits. This number applies only to guests using nested paging. When this field is zero, refer to the PhysAddrSize field for the maximum guest physical address size.
Fixes: 24c82e576b78 ("KVM: Sanitize cpuid") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210623230552.4027702-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/cpuid.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -844,8 +844,14 @@ static inline int __do_cpuid_func(struct unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U); unsigned phys_as = entry->eax & 0xff;
- if (!g_phys_as) + /* + * Use bare metal's MAXPHADDR if the CPU doesn't report guest + * MAXPHYADDR separately, or if TDP (NPT) is disabled, as the + * guest version "applies only to guests using nested paging". + */ + if (!g_phys_as || !tdp_enabled) g_phys_as = phys_as; + entry->eax = g_phys_as | (virt_as << 8); entry->edx = 0; cpuid_entry_override(entry, CPUID_8000_0008_EBX);