The patch below does not apply to the 5.11-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From a835429cda91621fca915d80672a157b47738afb Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Thu, 25 Mar 2021 13:01:17 -0700
Subject: [PATCH] KVM: x86/mmu: Ensure TLBs are flushed when yielding during
GFN range zap
When flushing a range of GFNs across multiple roots, ensure any pending
flush from a previous root is honored before yielding while walking the
tables of the current root.
Note, kvm_tdp_mmu_zap_gfn_range() now intentionally overwrites its local
"flush" with the result to avoid redundant flushes. zap_gfn_range()
preserves and return the incoming "flush", unless of course the flush was
performed prior to yielding and no new flush was triggered.
Fixes: 1af4a96025b3 ("KVM: x86/mmu: Yield in TDU MMU iter even if no SPTES changed")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210325200119.1359384-2-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index d78915019b08..f80648ac1d15 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -86,7 +86,7 @@ static inline struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm,
list_for_each_entry(_root, &_kvm->arch.tdp_mmu_roots, link)
static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
- gfn_t start, gfn_t end, bool can_yield);
+ gfn_t start, gfn_t end, bool can_yield, bool flush);
void kvm_tdp_mmu_free_root(struct kvm *kvm, struct kvm_mmu_page *root)
{
@@ -99,7 +99,7 @@ void kvm_tdp_mmu_free_root(struct kvm *kvm, struct kvm_mmu_page *root)
list_del(&root->link);
- zap_gfn_range(kvm, root, 0, max_gfn, false);
+ zap_gfn_range(kvm, root, 0, max_gfn, false, false);
free_page((unsigned long)root->spt);
kmem_cache_free(mmu_page_header_cache, root);
@@ -678,20 +678,21 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm,
* scheduler needs the CPU or there is contention on the MMU lock. If this
* function cannot yield, it will not release the MMU lock or reschedule and
* the caller must ensure it does not supply too large a GFN range, or the
- * operation can cause a soft lockup.
+ * operation can cause a soft lockup. Note, in some use cases a flush may be
+ * required by prior actions. Ensure the pending flush is performed prior to
+ * yielding.
*/
static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
- gfn_t start, gfn_t end, bool can_yield)
+ gfn_t start, gfn_t end, bool can_yield, bool flush)
{
struct tdp_iter iter;
- bool flush_needed = false;
rcu_read_lock();
tdp_root_for_each_pte(iter, root, start, end) {
if (can_yield &&
- tdp_mmu_iter_cond_resched(kvm, &iter, flush_needed)) {
- flush_needed = false;
+ tdp_mmu_iter_cond_resched(kvm, &iter, flush)) {
+ flush = false;
continue;
}
@@ -709,11 +710,11 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
continue;
tdp_mmu_set_spte(kvm, &iter, 0);
- flush_needed = true;
+ flush = true;
}
rcu_read_unlock();
- return flush_needed;
+ return flush;
}
/*
@@ -728,7 +729,7 @@ bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, gfn_t start, gfn_t end)
bool flush = false;
for_each_tdp_mmu_root_yield_safe(kvm, root)
- flush |= zap_gfn_range(kvm, root, start, end, true);
+ flush = zap_gfn_range(kvm, root, start, end, true, flush);
return flush;
}
@@ -940,7 +941,7 @@ static int zap_gfn_range_hva_wrapper(struct kvm *kvm,
struct kvm_mmu_page *root, gfn_t start,
gfn_t end, unsigned long unused)
{
- return zap_gfn_range(kvm, root, start, end, false);
+ return zap_gfn_range(kvm, root, start, end, false, false);
}
int kvm_tdp_mmu_zap_hva_range(struct kvm *kvm, unsigned long start,
