From 365e319208442a0807a96e9ea4d0b1fa338f1929 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 10 Oct 2024 11:23:35 -0700 Subject: KVM: Pass in write/dirty to kvm_vcpu_map(), not kvm_vcpu_unmap() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Now that all kvm_vcpu_{,un}map() users pass "true" for @dirty, have them pass "true" as a @writable param to kvm_vcpu_map(), and thus create a read-only mapping when possible. Note, creating read-only mappings can be theoretically slower, as they don't play nice with fast GUP due to the need to break CoW before mapping the underlying PFN. But practically speaking, creating a mapping isn't a super hot path, and getting a writable mapping for reading is weird and confusing. Tested-by: Alex Bennée Signed-off-by: Sean Christopherson Tested-by: Dmitry Osipenko Signed-off-by: Paolo Bonzini Message-ID: <20241010182427.1434605-34-seanjc@google.com> --- virt/kvm/kvm_main.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'virt') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 0d59f47f099e..baa741c2b81c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3110,7 +3110,8 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn) } EXPORT_SYMBOL_GPL(gfn_to_page); -int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) +int __kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map, + bool writable) { struct kvm_follow_pfn kfp = { .slot = gfn_to_memslot(vcpu->kvm, gfn), @@ -3124,6 +3125,7 @@ int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) map->page = NULL; map->hva = NULL; map->gfn = gfn; + map->writable = writable; map->pfn = kvm_follow_pfn(&kfp); if (is_error_noslot_pfn(map->pfn)) @@ -3140,9 +3142,9 @@ int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) return map->hva ? 0 : -EFAULT; } -EXPORT_SYMBOL_GPL(kvm_vcpu_map); +EXPORT_SYMBOL_GPL(__kvm_vcpu_map); -void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty) +void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map) { if (!map->hva) return; @@ -3154,11 +3156,11 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty) memunmap(map->hva); #endif - if (dirty) + if (map->writable) kvm_vcpu_mark_page_dirty(vcpu, map->gfn); if (map->pinned_page) { - if (dirty) + if (map->writable) kvm_set_page_dirty(map->pinned_page); kvm_set_page_accessed(map->pinned_page); unpin_user_page(map->pinned_page); -- cgit v1.2.3