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Message-Id: <1407999713-3726-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> Date: Thu, 14 Aug 2014 15:01:52 +0800 From: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com> To: gleb@...nel.org Cc: avi.kivity@...il.com, mtosatti@...hat.com, pbonzini@...hat.com, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>, stable@...r.kernel.org, David Matlack <dmatlack@...gle.com> Subject: [PATCH 1/2] KVM: fix cache stale memslot info with correct mmio generation number We may cache the current mmio generation number and stale memslot info into spte, like this scenarioļ¼ CPU 0 CPU 1 page fault: add a new memslot read memslot and detecting its a mmio access update memslots update generation number read generation number cache the gpa and current gen number into spte So, if guest accesses the gpa later, it will generate a incorrect mmio exit This patch fixes it by updating the generation number after synchronize_srcu_expedited() that makes sure the generation number updated only if memslots update is finished Cc: stable@...r.kernel.org Cc: David Matlack <dmatlack@...gle.com> Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com> --- virt/kvm/kvm_main.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 33712fb..bb40df3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -96,7 +96,7 @@ static void hardware_disable_all(void); static void kvm_io_bus_destroy(struct kvm_io_bus *bus); static void update_memslots(struct kvm_memslots *slots, - struct kvm_memory_slot *new, u64 last_generation); + struct kvm_memory_slot *new); static void kvm_release_pfn_dirty(pfn_t pfn); static void mark_page_dirty_in_slot(struct kvm *kvm, @@ -687,8 +687,7 @@ static void sort_memslots(struct kvm_memslots *slots) } static void update_memslots(struct kvm_memslots *slots, - struct kvm_memory_slot *new, - u64 last_generation) + struct kvm_memory_slot *new) { if (new) { int id = new->id; @@ -699,8 +698,6 @@ static void update_memslots(struct kvm_memslots *slots, if (new->npages != npages) sort_memslots(slots); } - - slots->generation = last_generation + 1; } static int check_memory_region_flags(struct kvm_userspace_memory_region *mem) @@ -722,9 +719,12 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm, { struct kvm_memslots *old_memslots = kvm->memslots; - update_memslots(slots, new, kvm->memslots->generation); + /* ensure generation number is always increased. */ + slots->generation = old_memslots->generation; + update_memslots(slots, new); rcu_assign_pointer(kvm->memslots, slots); synchronize_srcu_expedited(&kvm->srcu); + slots->generation++; kvm_arch_memslots_updated(kvm); -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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