46 lines
1.5 KiB
Diff
46 lines
1.5 KiB
Diff
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From 63d3efed81ddf36acfec73910a84dee426450012 Mon Sep 17 00:00:00 2001
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From: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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Date: Wed, 15 May 2024 01:03:38 +0000
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Subject: [PATCH] KVM: dirty ring: add missing memory barrier mainline
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inclusion commit 4802bf910eee98312c4a9777ac2567e6a0445c46 category: bugfix
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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---------------------------------------------------------------
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The KVM_DIRTY_GFN_F_DIRTY flag ensures that the entry is valid. If
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the read of the fields are not ordered after the read of the flag,
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QEMU might see stale values.
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Cc: Gavin Shan <gshan@redhat.com>
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Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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Reviewed-by: Peter Xu <peterx@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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---
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accel/kvm/kvm-all.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
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index c477f7a635..e55b2b6a16 100644
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--- a/accel/kvm/kvm-all.c
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+++ b/accel/kvm/kvm-all.c
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@@ -661,7 +661,11 @@ static void kvm_dirty_ring_mark_page(KVMState *s, uint32_t as_id,
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static bool dirty_gfn_is_dirtied(struct kvm_dirty_gfn *gfn)
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{
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- return gfn->flags == KVM_DIRTY_GFN_F_DIRTY;
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+ /*
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+ * Read the flags before the value. Pairs with barrier in
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+ * KVM's kvm_dirty_ring_push() function.
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+ */
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+ return qatomic_load_acquire(&gfn->flags) == KVM_DIRTY_GFN_F_DIRTY;
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}
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static void dirty_gfn_set_collected(struct kvm_dirty_gfn *gfn)
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--
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2.27.0
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