| Message ID | 20240608001108.3296879-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/mmu: Rephrase comment about synthetic PFERR flags in #PF handler | expand |
On 6/8/2024 8:11 AM, Sean Christopherson wrote: > Reword the BUILD_BUG_ON() comment in the legacy #PF handler to explicitly > describe how asserting that synthetic PFERR flags are limited to bits 31:0 > protects KVM against inadvertently passing a synthetic flag to the common > page fault handler. > > No functional change intended. > > Suggested-by: Xiaoyao Li <xiaoyao.li@intel.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com> > --- > arch/x86/kvm/mmu/mmu.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 8d7115230739..2421d971ce1b 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4599,7 +4599,10 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, > if (WARN_ON_ONCE(error_code >> 32)) > error_code = lower_32_bits(error_code); > > - /* Ensure the above sanity check also covers KVM-defined flags. */ > + /* > + * Restrict KVM-defined flags to bits 63:32 so that it's impossible for > + * them to conflict with #PF error codes, which are limited to 32 bits. > + */ > BUILD_BUG_ON(lower_32_bits(PFERR_SYNTHETIC_MASK)); > > vcpu->arch.l1tf_flush_l1d = true; > > base-commit: b9adc10edd4e14e66db4f7289a88fdbfa45ae7a8
On Fri, 07 Jun 2024 17:11:08 -0700, Sean Christopherson wrote: > Reword the BUILD_BUG_ON() comment in the legacy #PF handler to explicitly > describe how asserting that synthetic PFERR flags are limited to bits 31:0 > protects KVM against inadvertently passing a synthetic flag to the common > page fault handler. > > No functional change intended. > > [...] Applied to kvm-x86 mmu, thanks! [1/1] KVM: x86/mmu: Rephrase comment about synthetic PFERR flags in #PF handler https://github.com/kvm-x86/linux/commit/caa727882937 -- https://github.com/kvm-x86/linux/tree/next
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 8d7115230739..2421d971ce1b 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4599,7 +4599,10 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, if (WARN_ON_ONCE(error_code >> 32)) error_code = lower_32_bits(error_code); - /* Ensure the above sanity check also covers KVM-defined flags. */ + /* + * Restrict KVM-defined flags to bits 63:32 so that it's impossible for + * them to conflict with #PF error codes, which are limited to 32 bits. + */ BUILD_BUG_ON(lower_32_bits(PFERR_SYNTHETIC_MASK)); vcpu->arch.l1tf_flush_l1d = true;
Reword the BUILD_BUG_ON() comment in the legacy #PF handler to explicitly describe how asserting that synthetic PFERR flags are limited to bits 31:0 protects KVM against inadvertently passing a synthetic flag to the common page fault handler. No functional change intended. Suggested-by: Xiaoyao Li <xiaoyao.li@intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/mmu/mmu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) base-commit: b9adc10edd4e14e66db4f7289a88fdbfa45ae7a8