| Message ID | 20200415214414.10194-2-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/mmu: Minor cleanup in try_async_pf() | expand |
On Wed, Apr 15, 2020 at 2:44 PM Sean Christopherson <sean.j.christopherson@intel.com> wrote: > > Explicitly set @writable to false in try_async_pf() if the GFN->PFN > translation is short-circuited due to the requested GFN not being > visible to L2. > > Leaving @writable ('map_writable' in the callers) uninitialized is ok > in that it's never actually consumed, but one has to track it all the > way through set_spte() being short-circuited by set_mmio_spte() to > understand that the uninitialized variable is benign, and relying on > @writable being ignored is an unnecessary risk. Explicitly setting > @writable also aligns try_async_pf() with __gfn_to_pfn_memslot(). > > Jim Mattson <jmattson@google.com> Go ahead and preface the above with Reviewed-by: > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > arch/x86/kvm/mmu/mmu.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index c6ea6032c222..6d6cb9416179 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4090,6 +4090,7 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, > */ > if (is_guest_mode(vcpu) && !kvm_is_visible_gfn(vcpu->kvm, gfn)) { > *pfn = KVM_PFN_NOSLOT; > + *writable = false; > return false; > } > > -- > 2.26.0 >
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index c6ea6032c222..6d6cb9416179 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4090,6 +4090,7 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, */ if (is_guest_mode(vcpu) && !kvm_is_visible_gfn(vcpu->kvm, gfn)) { *pfn = KVM_PFN_NOSLOT; + *writable = false; return false; }
Explicitly set @writable to false in try_async_pf() if the GFN->PFN translation is short-circuited due to the requested GFN not being visible to L2. Leaving @writable ('map_writable' in the callers) uninitialized is ok in that it's never actually consumed, but one has to track it all the way through set_spte() being short-circuited by set_mmio_spte() to understand that the uninitialized variable is benign, and relying on @writable being ignored is an unnecessary risk. Explicitly setting @writable also aligns try_async_pf() with __gfn_to_pfn_memslot(). Jim Mattson <jmattson@google.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/mmu/mmu.c | 1 + 1 file changed, 1 insertion(+)