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KVM: x86/mmu: Ensure TLBs are flushed when yielding during GFN range zap

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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: 1af4a96025 ("KVM: x86/mmu: Yield in TDU MMU iter even if no SPTES changed")
Cc: stable@vger.kernel.org
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210325200119.1359384-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-03-25 13:01:17 -07:00 committed by Paolo Bonzini
parent 1e28eed176
commit a835429cda
1 changed files with 12 additions and 11 deletions
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23
arch/x86/kvm/mmu/tdp_mmu.c
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@ -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,