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Commit 6ba66178 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Avi Kivity
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KVM guest: do not batch pte updates from interrupt context 

Commit b8bcfe99 made paravirt pte updates synchronous in interrupt
context.

Unfortunately the KVM pv mmu code caches the lazy/nonlazy mode
internally, so a pte update from interrupt context during a lazy mmu
operation can be batched while it should be performed synchronously.

https://bugzilla.redhat.com/show_bug.cgi?id=518022



Drop the internal mode variable and use paravirt_get_lazy_mode(), which
returns the correct state.

Cc: stable@kernel.org
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 65a82211

arch/x86/kernel/kvm.c

+1 −6
Original line number Diff line number Diff line
@@ -34,7 +34,6 @@ 
struct kvm_para_state {

	u8 mmu_queue[MMU_QUEUE_SIZE];

	int mmu_queue_len;

	enum paravirt_lazy_mode mode;

};



static DEFINE_PER_CPU(struct kvm_para_state, para_state);
@@ -77,7 +76,7 @@ static void kvm_deferred_mmu_op(void *buffer, int len) 
{

	struct kvm_para_state *state = kvm_para_state();



	if (state->mode != PARAVIRT_LAZY_MMU) {

	if (paravirt_get_lazy_mode() != PARAVIRT_LAZY_MMU) {

		kvm_mmu_op(buffer, len);

		return;

	}
@@ -185,10 +184,7 @@ static void kvm_release_pt(unsigned long pfn) 


static void kvm_enter_lazy_mmu(void)

{

	struct kvm_para_state *state = kvm_para_state();



	paravirt_enter_lazy_mmu();

	state->mode = paravirt_get_lazy_mode();

}



static void kvm_leave_lazy_mmu(void)
@@ -197,7 +193,6 @@ static void kvm_leave_lazy_mmu(void) 


	mmu_queue_flush(state);

	paravirt_leave_lazy_mmu();

	state->mode = paravirt_get_lazy_mode();

}



static void __init paravirt_ops_setup(void)