From 873dd122172f8cce329113cfb0dfe3d2344d80c0 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 18 Mar 2022 12:30:32 -0400 Subject: Revert "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()" This reverts commit cf3e26427c08ad9015956293ab389004ac6a338e. Multi-vCPU Hyper-V guests started crashing randomly on boot with the latest kvm/queue and the problem can be bisected the problem to this particular patch. Basically, I'm not able to boot e.g. 16-vCPU guest successfully anymore. Both Intel and AMD seem to be affected. Reverting the commit saves the day. Reported-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 4 ++-- arch/x86/kvm/mmu/tdp_mmu.c | 41 ++++++++++++++++++++++++++++++----------- arch/x86/kvm/mmu/tdp_mmu.h | 8 +++++++- 3 files changed, 39 insertions(+), 14 deletions(-) (limited to 'arch/x86/kvm/mmu') diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 3b8da8b0745e..51671cb34fb6 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5842,8 +5842,8 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) if (is_tdp_mmu_enabled(kvm)) { for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) - flush = kvm_tdp_mmu_zap_leafs(kvm, i, gfn_start, - gfn_end, true, flush); + flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, gfn_start, + gfn_end, flush); } if (flush) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 7f63e1a704e3..e7e7876251b3 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -906,8 +906,10 @@ bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) } /* - * Zap leafs SPTEs for the range of gfns, [start, end). Returns true if SPTEs - * have been cleared and a TLB flush is needed before releasing the MMU lock. + * Tears down the mappings for the range of gfns, [start, end), and frees the + * non-root pages mapping GFNs strictly within that range. Returns true if + * SPTEs have been cleared and a TLB flush is needed before releasing the + * MMU lock. * * If can_yield is true, will release the MMU lock and reschedule if the * scheduler needs the CPU or there is contention on the MMU lock. If this @@ -915,25 +917,42 @@ bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) * the caller must ensure it does not supply too large a GFN range, or the * operation can cause a soft lockup. */ -static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root, - gfn_t start, gfn_t end, bool can_yield, bool flush) +static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end, bool can_yield, bool flush) { + bool zap_all = (start == 0 && end >= tdp_mmu_max_gfn_host()); struct tdp_iter iter; + /* + * No need to try to step down in the iterator when zapping all SPTEs, + * zapping the top-level non-leaf SPTEs will recurse on their children. + */ + int min_level = zap_all ? root->role.level : PG_LEVEL_4K; + end = min(end, tdp_mmu_max_gfn_host()); lockdep_assert_held_write(&kvm->mmu_lock); rcu_read_lock(); - for_each_tdp_pte_min_level(iter, root, PG_LEVEL_4K, start, end) { + for_each_tdp_pte_min_level(iter, root, min_level, start, end) { if (can_yield && tdp_mmu_iter_cond_resched(kvm, &iter, flush, false)) { flush = false; continue; } - if (!is_shadow_present_pte(iter.old_spte) || + if (!is_shadow_present_pte(iter.old_spte)) + continue; + + /* + * If this is a non-last-level SPTE that covers a larger range + * than should be zapped, continue, and zap the mappings at a + * lower level, except when zapping all SPTEs. + */ + if (!zap_all && + (iter.gfn < start || + iter.gfn + KVM_PAGES_PER_HPAGE(iter.level) > end) && !is_last_spte(iter.old_spte, iter.level)) continue; @@ -960,13 +979,13 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root, * SPTEs have been cleared and a TLB flush is needed before releasing the * MMU lock. */ -bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start, gfn_t end, - bool can_yield, bool flush) +bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start, + gfn_t end, bool can_yield, bool flush) { struct kvm_mmu_page *root; for_each_tdp_mmu_root_yield_safe(kvm, root, as_id) - flush = tdp_mmu_zap_leafs(kvm, root, start, end, can_yield, false); + flush = zap_gfn_range(kvm, root, start, end, can_yield, flush); return flush; } @@ -1214,8 +1233,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, bool flush) { - return kvm_tdp_mmu_zap_leafs(kvm, range->slot->as_id, range->start, - range->end, range->may_block, flush); + return __kvm_tdp_mmu_zap_gfn_range(kvm, range->slot->as_id, range->start, + range->end, range->may_block, flush); } typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter, diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index 54bc8118c40a..5e5ef2576c81 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -15,8 +15,14 @@ __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root) void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root, bool shared); -bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start, +bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start, gfn_t end, bool can_yield, bool flush); +static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, + gfn_t start, gfn_t end, bool flush) +{ + return __kvm_tdp_mmu_zap_gfn_range(kvm, as_id, start, end, true, flush); +} + bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp); void kvm_tdp_mmu_zap_all(struct kvm *kvm); void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm); -- cgit v1.2.3