| Message ID | 20190926231824.149014-4-bgardon@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kvm: mmu: Rework the x86 TDP direct mapped case | expand |
On Thu, Sep 26, 2019 at 04:17:59PM -0700, Ben Gardon wrote: > Simplify use of the MMU page cache by allocating pages pre-zeroed. This > ensures that future code does not accidentally add non-zeroed memory to > the paging structure and moves the work of zeroing page page out from > under the MMU lock. Ha, this *just* came up in a different series[*]. Unless there is a hard dependency on the rest of this series, it'd be nice to tackle this separately so that we can fully understand the tradeoffs. And it could be merged early/independently as well. [*] https://patchwork.kernel.org/patch/11228487/#23025353 > > Signed-off-by: Ben Gardon <bgardon@google.com> > --- > arch/x86/kvm/mmu.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 7e5ab9c6e2b09..1ecd6d51c0ee0 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -1037,7 +1037,7 @@ static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache, > if (cache->nobjs >= min) > return 0; > while (cache->nobjs < ARRAY_SIZE(cache->objects)) { > - page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT); > + page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO); > if (!page) > return cache->nobjs >= min ? 0 : -ENOMEM; > cache->objects[cache->nobjs++] = page; > @@ -2548,7 +2548,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > if (level > PT_PAGE_TABLE_LEVEL && need_sync) > flush |= kvm_sync_pages(vcpu, gfn, &invalid_list); > } > - clear_page(sp->spt); > trace_kvm_mmu_get_page(sp, true); > > kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); > -- > 2.23.0.444.g18eeb5a265-goog >
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 7e5ab9c6e2b09..1ecd6d51c0ee0 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1037,7 +1037,7 @@ static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache, if (cache->nobjs >= min) return 0; while (cache->nobjs < ARRAY_SIZE(cache->objects)) { - page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT); + page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO); if (!page) return cache->nobjs >= min ? 0 : -ENOMEM; cache->objects[cache->nobjs++] = page; @@ -2548,7 +2548,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, if (level > PT_PAGE_TABLE_LEVEL && need_sync) flush |= kvm_sync_pages(vcpu, gfn, &invalid_list); } - clear_page(sp->spt); trace_kvm_mmu_get_page(sp, true); kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
Simplify use of the MMU page cache by allocating pages pre-zeroed. This ensures that future code does not accidentally add non-zeroed memory to the paging structure and moves the work of zeroing page page out from under the MMU lock. Signed-off-by: Ben Gardon <bgardon@google.com> --- arch/x86/kvm/mmu.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)