diff options
| author | Andrew Honig <ahonig@google.com> | 2013-03-29 09:35:21 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-25 21:23:48 -0700 |
| commit | d715cdddb8cdf1c17bf1c5ff8fcc9852cd6ba79e (patch) | |
| tree | bd4511997d89bebe33b9395789c8395c017fc93d /virt | |
| parent | 17f13c27702d90899081bf70134132ed5f25158e (diff) | |
KVM: Allow cross page reads and writes from cached translations.
commit 8f964525a121f2ff2df948dac908dcc65be21b5b upstream.
This patch adds support for kvm_gfn_to_hva_cache_init functions for
reads and writes that will cross a page. If the range falls within
the same memslot, then this will be a fast operation. If the range
is split between two memslots, then the slower kvm_read_guest and
kvm_write_guest are used.
Tested: Test against kvm_clock unit tests.
Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 39 |
1 files changed, 31 insertions, 8 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 88dde44bc07b..caa3bb158d22 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1375,20 +1375,38 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data, } int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc, - gpa_t gpa) + gpa_t gpa, unsigned long len) { struct kvm_memslots *slots = kvm_memslots(kvm); int offset = offset_in_page(gpa); - gfn_t gfn = gpa >> PAGE_SHIFT; + gfn_t start_gfn = gpa >> PAGE_SHIFT; + gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT; + gfn_t nr_pages_needed = end_gfn - start_gfn + 1; + gfn_t nr_pages_avail; ghc->gpa = gpa; ghc->generation = slots->generation; - ghc->memslot = __gfn_to_memslot(slots, gfn); - ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL); - if (!kvm_is_error_hva(ghc->hva)) + ghc->len = len; + ghc->memslot = gfn_to_memslot(kvm, start_gfn); + ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn, &nr_pages_avail); + if (!kvm_is_error_hva(ghc->hva) && nr_pages_avail >= nr_pages_needed) { ghc->hva += offset; - else - return -EFAULT; + } else { + /* + * If the requested region crosses two memslots, we still + * verify that the entire region is valid here. + */ + while (start_gfn <= end_gfn) { + ghc->memslot = gfn_to_memslot(kvm, start_gfn); + ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn, + &nr_pages_avail); + if (kvm_is_error_hva(ghc->hva)) + return -EFAULT; + start_gfn += nr_pages_avail; + } + /* Use the slow path for cross page reads and writes. */ + ghc->memslot = NULL; + } return 0; } @@ -1400,8 +1418,13 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, struct kvm_memslots *slots = kvm_memslots(kvm); int r; + BUG_ON(len > ghc->len); + if (slots->generation != ghc->generation) - kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa); + kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len); + + if (unlikely(!ghc->memslot)) + return kvm_write_guest(kvm, ghc->gpa, data, len); if (kvm_is_error_hva(ghc->hva)) return -EFAULT; |