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[3.13.y-ckt,83/95] KVM: use slowpath for cross page cached accesses

Message ID 1432753243-16151-84-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa May 27, 2015, 7 p.m. UTC 
3.13.11-ckt21 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com>

commit ca3f0874723fad81d0c701b63ae3a17a408d5f25 upstream.

kvm_write_guest_cached() does not mark all written pages as dirty and
code comments in kvm_gfn_to_hva_cache_init() talk about NULL memslot
with cross page accesses.  Fix all the easy way.

The check is '<= 1' to have the same result for 'len = 0' cache anywhere
in the page.  (nr_pages_needed is 0 on page boundary.)

Fixes: 8f964525a121 ("KVM: Allow cross page reads and writes from cached translations.")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Message-Id: <20150408121648.GA3519@potion.brq.redhat.com>
Reviewed-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 virt/kvm/kvm_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8d2a98a..db50f4c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1559,8 +1559,8 @@  int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 	ghc->generation = slots->generation;
 	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 = gfn_to_hva_many(ghc->memslot, start_gfn, NULL);
+	if (!kvm_is_error_hva(ghc->hva) && nr_pages_needed <= 1) {
 		ghc->hva += offset;
 	} else {
 		/*