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Subject[PATCH v4 13/29] KVM: x86/mmu: Don't rely on page-track mechanism to flush on memslot change
From
Call kvm_mmu_zap_all_fast() directly when flushing a memslot instead of
bouncing through the page-track mechanism. KVM (unfortunately) needs to
zap and flush all page tables on memslot DELETE/MOVE irrespective of
whether KVM is shadowing guest page tables.

This will allow changing KVM to register a page-track notifier on the
first shadow root allocation, and will also allow deleting the misguided
kvm_page_track_flush_slot() hook itself once KVM-GT also moves to a
different method for reacting to memslot changes.

No functional change intended.

Cc: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20221110014821.1548347-2-seanjc@google.com
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/mmu.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c6dee659d592..79ea57396d97 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6199,13 +6199,6 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
}

-static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
- struct kvm_memory_slot *slot,
- struct kvm_page_track_notifier_node *node)
-{
- kvm_mmu_zap_all_fast(kvm);
-}
-
int kvm_mmu_init_vm(struct kvm *kvm)
{
struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker;
@@ -6223,7 +6216,6 @@ int kvm_mmu_init_vm(struct kvm *kvm)
}

node->track_write = kvm_mmu_pte_write;
- node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
kvm_page_track_register_notifier(kvm, node);

kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache;
@@ -6765,6 +6757,8 @@ void kvm_arch_flush_shadow_all(struct kvm *kvm)
void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot)
{
+ kvm_mmu_zap_all_fast(kvm);
+
kvm_page_track_flush_slot(kvm, slot);
}

--
2.41.0.487.g6d72f3e995-goog
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