diff options
| author | Mathias Krause <minipli@grsecurity.net> | 2023-03-22 04:37:28 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-03-22 17:47:24 +0300 |
| commit | e40bcf9f3a187126ce74a05d3b177fc16874446f (patch) | |
| tree | ba80c0a3038d28ecef1574cd333235951ade4fc3 /arch/x86/kvm/x86.c | |
| parent | 01b31714bd90be2784f7145bf93b7f78f3d081e1 (diff) | |
| download | linux-e40bcf9f3a187126ce74a05d3b177fc16874446f.tar.xz | |
KVM: x86: Ignore CR0.WP toggles in non-paging mode
If paging is disabled, there are no permission bits to emulate.
Micro-optimize this case to avoid unnecessary work.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20230322013731.102955-4-minipli@grsecurity.net
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c6d909778b2c..8a66ac7a4878 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -908,14 +908,20 @@ void kvm_post_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned lon { /* * CR0.WP is incorporated into the MMU role, but only for non-nested, - * indirect shadow MMUs. If TDP is enabled, the MMU's metadata needs - * to be updated, e.g. so that emulating guest translations does the - * right thing, but there's no need to unload the root as CR0.WP - * doesn't affect SPTEs. + * indirect shadow MMUs. If paging is disabled, no updates are needed + * as there are no permission bits to emulate. If TDP is enabled, the + * MMU's metadata needs to be updated, e.g. so that emulating guest + * translations does the right thing, but there's no need to unload the + * root as CR0.WP doesn't affect SPTEs. */ - if (tdp_enabled && (cr0 ^ old_cr0) == X86_CR0_WP) { - kvm_init_mmu(vcpu); - return; + if ((cr0 ^ old_cr0) == X86_CR0_WP) { + if (!(cr0 & X86_CR0_PG)) + return; + + if (tdp_enabled) { + kvm_init_mmu(vcpu); + return; + } } if ((cr0 ^ old_cr0) & X86_CR0_PG) { |