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Date: Mon, 2 Aug 2021 21:33:18 +0300
From: Maxim Levitsky <mlevitsk@...hat.com>
To: kvm@...r.kernel.org
Cc: Wanpeng Li <wanpengli@...cent.com>,
Thomas Gleixner <tglx@...utronix.de>,
Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...en8.de>,
Sean Christopherson <seanjc@...gle.com>,
Jim Mattson <jmattson@...gle.com>,
x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
64-BIT)), Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v3 01/12] Revert "KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock"
From: Sean Christopherson <seanjc@...gle.com>
This together with the next patch will fix a future race between
kvm_zap_gfn_range and the page fault handler, which will happen
when AVIC memslot is going to be only partially disabled.
This is based on a patch suggested by Sean Christopherson:
https://lkml.org/lkml/2021/7/22/1025
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
arch/x86/kvm/mmu/mmu.c | 19 ++++++++-----------
arch/x86/kvm/mmu/tdp_mmu.c | 15 ++++-----------
arch/x86/kvm/mmu/tdp_mmu.h | 11 ++++-------
3 files changed, 16 insertions(+), 29 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a8cdfd8d45c4..9d78cb1c0f35 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5638,8 +5638,9 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
int i;
bool flush = false;
+ write_lock(&kvm->mmu_lock);
+
if (kvm_memslots_have_rmaps(kvm)) {
- write_lock(&kvm->mmu_lock);
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
slots = __kvm_memslots(kvm, i);
kvm_for_each_memslot(memslot, slots) {
@@ -5659,22 +5660,18 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
}
if (flush)
kvm_flush_remote_tlbs_with_address(kvm, gfn_start, gfn_end);
- write_unlock(&kvm->mmu_lock);
}
if (is_tdp_mmu_enabled(kvm)) {
- flush = false;
-
- read_lock(&kvm->mmu_lock);
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, gfn_start,
- gfn_end, flush, true);
- if (flush)
- kvm_flush_remote_tlbs_with_address(kvm, gfn_start,
- gfn_end);
-
- read_unlock(&kvm->mmu_lock);
+ gfn_end, flush);
}
+
+ if (flush)
+ kvm_flush_remote_tlbs_with_address(kvm, gfn_start, gfn_end);
+
+ write_unlock(&kvm->mmu_lock);
}
static bool slot_rmap_write_protect(struct kvm *kvm,
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 43f12f5d12c0..3e0222ce3f4e 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -777,21 +777,15 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
* 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 shared is true, this thread holds the MMU lock in read mode and must
- * account for the possibility that other threads are modifying the paging
- * structures concurrently. If shared is false, this thread should hold the
- * MMU in write mode.
*/
bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start,
- gfn_t end, bool can_yield, bool flush,
- bool shared)
+ gfn_t end, bool can_yield, bool flush)
{
struct kvm_mmu_page *root;
- for_each_tdp_mmu_root_yield_safe(kvm, root, as_id, shared)
+ for_each_tdp_mmu_root_yield_safe(kvm, root, as_id, false)
flush = zap_gfn_range(kvm, root, start, end, can_yield, flush,
- shared);
+ false);
return flush;
}
@@ -803,8 +797,7 @@ void kvm_tdp_mmu_zap_all(struct kvm *kvm)
int i;
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
- flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, max_gfn,
- flush, false);
+ flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, max_gfn, flush);
if (flush)
kvm_flush_remote_tlbs(kvm);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index b224d126adf9..358f447d4012 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -20,14 +20,11 @@ void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root,
bool shared);
bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start,
- gfn_t end, bool can_yield, bool flush,
- bool shared);
+ 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,
- bool shared)
+ gfn_t start, gfn_t end, bool flush)
{
- return __kvm_tdp_mmu_zap_gfn_range(kvm, as_id, start, end, true, flush,
- shared);
+ return __kvm_tdp_mmu_zap_gfn_range(kvm, as_id, start, end, true, flush);
}
static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
{
@@ -44,7 +41,7 @@ static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
*/
lockdep_assert_held_write(&kvm->mmu_lock);
return __kvm_tdp_mmu_zap_gfn_range(kvm, kvm_mmu_page_as_id(sp),
- sp->gfn, end, false, false, false);
+ sp->gfn, end, false, false);
}
void kvm_tdp_mmu_zap_all(struct kvm *kvm);
--
2.26.3
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