diff options
| author | Sean Christopherson <seanjc@google.com> | 2024-10-10 11:23:36 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-10-25 12:59:08 -0400 |
| commit | 2e5fdf60a9a69971b5e642d32e09bd6b0223f47c (patch) | |
| tree | 2e1ca3e5c6a9e23f56ed6dba2b010aa9815adb1e /virt/kvm | |
| parent | 365e319208442a0807a96e9ea4d0b1fa338f1929 (diff) | |
KVM: Get writable mapping for __kvm_vcpu_map() only when necessary
When creating a memory map for read, don't request a writable pfn from the
primary MMU. While 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, 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 <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-35-seanjc@google.com>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/kvm_main.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index baa741c2b81c..49ac13872e09 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3116,7 +3116,7 @@ int __kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map, struct kvm_follow_pfn kfp = { .slot = gfn_to_memslot(vcpu->kvm, gfn), .gfn = gfn, - .flags = FOLL_WRITE, + .flags = writable ? FOLL_WRITE : 0, .refcounted_page = &map->pinned_page, .pin = true, }; |