From: Babu Moger <babu.moger@amd.com>
Date: Thu, 12 Nov 2020 16:17:56 -0600
Subject: KVM: x86: Introduce cr3_lm_rsvd_bits in kvm_vcpu_arch
Git-commit: 0107973a80adad5b73232d3fbcd26f710ab1f851
Patch-mainline: v5.10-rc4
References: bsc#1178995
SEV guests fail to boot on a system that supports the PCID feature.
While emulating the RSM instruction, KVM reads the guest CR3
and calls kvm_set_cr3(). If the vCPU is in the long mode,
kvm_set_cr3() does a sanity check for the CR3 value. In this case,
it validates whether the value has any reserved bits set. The
reserved bit range is 63:cpuid_maxphysaddr(). When AMD memory
encryption is enabled, the memory encryption bit is set in the CR3
value. The memory encryption bit may fall within the KVM reserved
bit range, causing the KVM emulation failure.
Introduce a new field cr3_lm_rsvd_bits in kvm_vcpu_arch which will
cache the reserved bits in the CR3 value. This will be initialized
to rsvd_bits(cpuid_maxphyaddr(vcpu), 63).
If the architecture has any special bits(like AMD SEV encryption bit)
that needs to be masked from the reserved bits, should be cleared
in vendor specific kvm_x86_ops.vcpu_after_set_cpuid handler.
Fixes: a780a3ea628268b2 ("KVM: X86: Fix reserved bits check for MOV to CR3")
Signed-off-by: Babu Moger <babu.moger@amd.com>
Message-Id: <160521947657.32054.3264016688005356563.stgit@bmoger-ubuntu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/cpuid.c | 3 +++
arch/x86/kvm/x86.c | 2 +-
3 files changed, 5 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -657,6 +657,7 @@ struct kvm_vcpu_arch {
int cpuid_nent;
struct kvm_cpuid_entry2 cpuid_entries[KVM_MAX_CPUID_ENTRIES];
+ unsigned long cr3_lm_rsvd_bits;
int maxphyaddr;
/* emulate context */
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -149,6 +149,9 @@ int kvm_update_cpuid(struct kvm_vcpu *vc
kvm_mmu_reset_context(vcpu);
kvm_pmu_refresh(vcpu);
+
+ vcpu->arch.cr3_lm_rsvd_bits = rsvd_bits(cpuid_maxphyaddr(vcpu), 63);
+
return 0;
}
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -985,7 +985,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, u
}
if (is_long_mode(vcpu) &&
- (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63)))
+ (cr3 & vcpu->arch.cr3_lm_rsvd_bits))
return 1;
else if (is_pae_paging(vcpu) &&
!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))