From: Sean Christopherson seanjc@google.com
[ Upstream commit a835429cda91621fca915d80672a157b47738afb ]
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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/mmu/tdp_mmu.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 65c9172dcdf9..50c088a41dee 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -111,7 +111,7 @@ bool is_tdp_mmu_root(struct kvm *kvm, hpa_t hpa) }
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) { @@ -124,7 +124,7 @@ 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); @@ -506,20 +506,21 @@ 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; }
@@ -537,11 +538,11 @@ 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; }
/* @@ -556,7 +557,7 @@ 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; } @@ -759,7 +760,7 @@ 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,