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authorMaxim Levitsky <mlevitsk@redhat.com>2021-11-15 15:18:37 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2021-11-18 02:03:42 -0500
commitb8453cdcf26020030da182f0156d7bf59ae5719f (patch)
tree40b891fefa34a57ea3a7e015cb6a7dc2219036f7 /arch/x86
parentaf957eebfcc17433ee83ab85b1195a933ab5049c (diff)
KVM: x86/mmu: include EFER.LMA in extended mmu role
Incorporate EFER.LMA into kvm_mmu_extended_role, as it used to compute the guest root level and is not reflected in kvm_mmu_page_role.level when TDP is in use. When simply running the guest, it is impossible for EFER.LMA and kvm_mmu.root_level to get out of sync, as the guest cannot transition from PAE paging to 64-bit paging without toggling CR0.PG, i.e. without first bouncing through a different MMU context. And stuffing guest state via KVM_SET_SREGS{,2} also ensures a full MMU context reset. However, if KVM_SET_SREGS{,2} is followed by KVM_SET_NESTED_STATE, e.g. to set guest state when migrating the VM while L2 is active, the vCPU state will reflect L2, not L1. If L1 is using TDP for L2, then root_mmu will have been configured using L2's state, despite not being used for L2. If L2.EFER.LMA != L1.EFER.LMA, and L2 is using PAE paging, then root_mmu will be configured for guest PAE paging, but will match the mmu_role for 64-bit paging and cause KVM to not reconfigure root_mmu on the next nested VM-Exit. Alternatively, the root_mmu's role could be invalidated after a successful KVM_SET_NESTED_STATE that yields vcpu->arch.mmu != vcpu->arch.root_mmu, i.e. that switches the active mmu to guest_mmu, but doing so is unnecessarily tricky, and not even needed if L1 and L2 do have the same role (e.g., they are both 64-bit guests and run with the same CR4). Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20211115131837.195527-3-mlevitsk@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/kvm_host.h1
-rw-r--r--arch/x86/kvm/mmu/mmu.c1
2 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 33e3292233f3..e977634333d4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -363,6 +363,7 @@ union kvm_mmu_extended_role {
unsigned int cr4_smap:1;
unsigned int cr4_smep:1;
unsigned int cr4_la57:1;
+ unsigned int efer_lma:1;
};
};
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 04c00c34517e..0571b1c7bf6f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4682,6 +4682,7 @@ static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu,
/* PKEY and LA57 are active iff long mode is active. */
ext.cr4_pke = ____is_efer_lma(regs) && ____is_cr4_pke(regs);
ext.cr4_la57 = ____is_efer_lma(regs) && ____is_cr4_la57(regs);
+ ext.efer_lma = ____is_efer_lma(regs);
}
ext.valid = 1;