From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Yu Zhang <yu.c.zhang@linux.intel.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH 12/54] KVM: x86/mmu: Drop the intermediate "transient" __kvm_sync_page()
Date: Tue, 22 Jun 2021 10:56:57 -0700 [thread overview]
Message-ID: <20210622175739.3610207-13-seanjc@google.com> (raw)
In-Reply-To: <20210622175739.3610207-1-seanjc@google.com>
Nove the kvm_unlink_unsync_page() call out of kvm_sync_page() and into
it's sole caller, and fold __kvm_sync_page() into kvm_sync_page() since
the latter becomes a pure pass-through. There really should be no reason
for code to do a complete sync of a shadow page outside of the full
kvm_mmu_sync_roots(), e.g. the one use case that creeped in turned out to
be flawed and counter-productive.
Update the comment in kvm_mmu_get_page() regarding its sync_page() usage,
which is anything but obvious.
Drop the stale comment about @sp->gfn needing to be write-protected, as
it directly contradicts the kvm_mmu_get_page() usage.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/mmu.c | 36 +++++++++++++++++++-----------------
1 file changed, 19 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 2e2d66319325..77296ce6215f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1780,18 +1780,6 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \
if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
-/* @sp->gfn should be write-protected at the call site */
-static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
- struct list_head *invalid_list)
-{
- if (vcpu->arch.mmu->sync_page(vcpu, sp) == 0) {
- kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
- return false;
- }
-
- return true;
-}
-
static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm,
struct list_head *invalid_list,
bool remote_flush)
@@ -1833,8 +1821,12 @@ static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list)
{
- kvm_unlink_unsync_page(vcpu->kvm, sp);
- return __kvm_sync_page(vcpu, sp, invalid_list);
+ if (vcpu->arch.mmu->sync_page(vcpu, sp) == 0) {
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
+ return false;
+ }
+
+ return true;
}
struct mmu_page_path {
@@ -1931,6 +1923,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
}
for_each_sp(pages, sp, parents, i) {
+ kvm_unlink_unsync_page(vcpu->kvm, sp);
flush |= kvm_sync_page(vcpu, sp, &invalid_list);
mmu_pages_clear_parents(&parents);
}
@@ -2008,10 +2001,19 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
goto trace_get_page;
if (sp->unsync) {
- /* The page is good, but __kvm_sync_page might still end
- * up zapping it. If so, break in order to rebuild it.
+ /*
+ * The page is good, but is stale. "Sync" the page to
+ * get the latest guest state, but don't write-protect
+ * the page and don't mark it synchronized! KVM needs
+ * to ensure the mapping is valid, but doesn't need to
+ * fully sync (write-protect) the page until the guest
+ * invalidates the TLB mapping. This allows multiple
+ * SPs for a single gfn to be unsync.
+ *
+ * If the sync fails, the page is zapped. If so, break
+ * If so, break in order to rebuild it.
*/
- if (!__kvm_sync_page(vcpu, sp, &invalid_list))
+ if (!kvm_sync_page(vcpu, sp, &invalid_list))
break;
WARN_ON(!list_empty(&invalid_list));
--
2.32.0.288.g62a8d224e6-goog
next prev parent reply other threads:[~2021-06-22 17:59 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-22 17:56 [PATCH 00/54] KVM: x86/mmu: Bug fixes and summer cleaning Sean Christopherson
2021-06-22 17:56 ` [PATCH 01/54] KVM: x86/mmu: Remove broken WARN that fires on 32-bit KVM w/ nested EPT Sean Christopherson
2021-06-22 17:56 ` [PATCH 02/54] KVM: x86/mmu: Treat NX as used (not reserved) for all !TDP shadow MMUs Sean Christopherson
2021-06-22 17:56 ` [PATCH 03/54] KVM: x86: Properly reset MMU context at vCPU RESET/INIT Sean Christopherson
2021-06-23 13:59 ` Paolo Bonzini
2021-06-23 14:01 ` Paolo Bonzini
2021-06-23 14:50 ` Sean Christopherson
2021-06-22 17:56 ` [PATCH 04/54] KVM: x86/mmu: Use MMU's role to detect CR4.SMEP value in nested NPT walk Sean Christopherson
2021-06-22 17:56 ` [PATCH 05/54] Revert "KVM: x86/mmu: Drop kvm_mmu_extended_role.cr4_la57 hack" Sean Christopherson
2021-06-25 8:47 ` Yu Zhang
2021-06-25 8:57 ` Paolo Bonzini
2021-06-25 9:29 ` Yu Zhang
2021-06-25 10:25 ` Paolo Bonzini
2021-06-25 11:23 ` Yu Zhang
2021-06-22 17:56 ` [PATCH 06/54] KVM: x86: Force all MMUs to reinitialize if guest CPUID is modified Sean Christopherson
2021-06-22 17:56 ` [PATCH 07/54] KVM: x86: Alert userspace that KVM_SET_CPUID{,2} after KVM_RUN is broken Sean Christopherson
2021-06-23 14:16 ` Paolo Bonzini
2021-06-23 17:00 ` Jim Mattson
2021-06-23 17:11 ` Paolo Bonzini
2021-06-23 18:11 ` Jim Mattson
2021-06-23 18:49 ` Paolo Bonzini
2021-06-23 19:02 ` Jim Mattson
2021-06-23 19:53 ` Paolo Bonzini
2021-06-22 17:56 ` [PATCH 08/54] Revert "KVM: MMU: record maximum physical address width in kvm_mmu_extended_role" Sean Christopherson
2021-06-25 8:52 ` Yu Zhang
2021-06-22 17:56 ` [PATCH 09/54] KVM: x86/mmu: Unconditionally zap unsync SPs when creating >4k SP at GFN Sean Christopherson
2021-06-23 14:36 ` Paolo Bonzini
2021-06-23 15:08 ` Sean Christopherson
2021-06-23 16:38 ` Paolo Bonzini
2021-06-23 22:04 ` Sean Christopherson
2021-06-25 9:51 ` Yu Zhang
2021-06-25 10:26 ` Paolo Bonzini
2021-06-25 13:08 ` Yu Zhang
2021-06-22 17:56 ` [PATCH 10/54] KVM: x86/mmu: Replace EPT shadow page shenanigans with simpler check Sean Christopherson
2021-06-23 15:49 ` Paolo Bonzini
2021-06-23 16:17 ` Sean Christopherson
2021-06-23 16:41 ` Paolo Bonzini
2021-06-23 16:54 ` Sean Christopherson
2021-06-22 17:56 ` [PATCH 11/54] KVM: x86/mmu: WARN and zap SP when sync'ing if MMU role mismatches Sean Christopherson
2021-06-22 17:56 ` Sean Christopherson [this message]
2021-06-23 16:54 ` [PATCH 12/54] KVM: x86/mmu: Drop the intermediate "transient" __kvm_sync_page() Paolo Bonzini
2021-06-22 17:56 ` [PATCH 13/54] KVM: x86/mmu: Rename unsync helper and update related comments Sean Christopherson
2021-06-22 17:56 ` [PATCH 14/54] KVM: x86: Fix sizes used to pass around CR0, CR4, and EFER Sean Christopherson
2021-06-22 17:57 ` [PATCH 15/54] KVM: nSVM: Add a comment to document why nNPT uses vmcb01, not vCPU state Sean Christopherson
2021-06-23 17:06 ` Paolo Bonzini
2021-06-23 20:49 ` Sean Christopherson
2021-06-22 17:57 ` [PATCH 16/54] KVM: x86/mmu: Drop smep_andnot_wp check from "uses NX" for shadow MMUs Sean Christopherson
2021-06-23 17:11 ` Paolo Bonzini
2021-06-23 19:36 ` Sean Christopherson
2021-06-22 17:57 ` [PATCH 17/54] KVM: x86: Read and pass all CR0/CR4 role bits to shadow MMU helper Sean Christopherson
2021-06-22 17:57 ` [PATCH 18/54] KVM: x86/mmu: Move nested NPT reserved bit calculation into MMU proper Sean Christopherson
2021-06-23 17:13 ` Paolo Bonzini
2021-06-22 17:57 ` [PATCH 19/54] KVM: x86/mmu: Grab shadow root level from mmu_role for shadow MMUs Sean Christopherson
2021-06-22 17:57 ` [PATCH 20/54] KVM: x86/mmu: Add struct and helpers to retrieve MMU role bits from regs Sean Christopherson
2021-06-23 1:58 ` kernel test robot
2021-06-23 1:58 ` kernel test robot
2021-06-23 17:18 ` Paolo Bonzini
2021-06-22 17:57 ` [PATCH 21/54] KVM: x86/mmu: Consolidate misc updates into shadow_mmu_init_context() Sean Christopherson
2021-06-22 17:57 ` [PATCH 22/54] KVM: x86/mmu: Ignore CR0 and CR4 bits in nested EPT MMU role Sean Christopherson
2021-06-22 17:57 ` [PATCH 23/54] KVM: x86/mmu: Use MMU's role_regs, not vCPU state, to compute mmu_role Sean Christopherson
2021-06-22 17:57 ` [PATCH 24/54] KVM: x86/mmu: Rename "nxe" role bit to "efer_nx" for macro shenanigans Sean Christopherson
2021-06-22 17:57 ` [PATCH 25/54] KVM: x86/mmu: Add helpers to query mmu_role bits Sean Christopherson
2021-06-23 20:02 ` Paolo Bonzini
2021-06-23 20:47 ` Sean Christopherson
2021-06-23 20:53 ` Paolo Bonzini
2021-06-22 17:57 ` [PATCH 26/54] KVM: x86/mmu: Do not set paging-related bits in MMU role if CR0.PG=0 Sean Christopherson
2021-06-22 17:57 ` [PATCH 27/54] KVM: x86/mmu: Set CR4.PKE/LA57 in MMU role iff long mode is active Sean Christopherson
2021-06-22 17:57 ` [PATCH 28/54] KVM: x86/mmu: Always Set new mmu_role immediately after checking old role Sean Christopherson
2021-06-22 17:57 ` [PATCH 29/54] KVM: x86/mmu: Don't grab CR4.PSE for calculating shadow reserved bits Sean Christopherson
2021-06-22 17:57 ` [PATCH 30/54] KVM: x86/mmu: Use MMU's role to get CR4.PSE for computing rsvd bits Sean Christopherson
2021-06-22 17:57 ` [PATCH 31/54] KVM: x86/mmu: Drop vCPU param from reserved bits calculator Sean Christopherson
2021-06-22 17:57 ` [PATCH 32/54] KVM: x86/mmu: Use MMU's role to compute permission bitmask Sean Christopherson
2021-06-22 17:57 ` [PATCH 33/54] KVM: x86/mmu: Use MMU's role to compute PKRU bitmask Sean Christopherson
2021-06-22 17:57 ` [PATCH 34/54] KVM: x86/mmu: Use MMU's roles to compute last non-leaf level Sean Christopherson
2021-06-22 17:57 ` [PATCH 35/54] KVM: x86/mmu: Use MMU's role to detect EFER.NX in guest page walk Sean Christopherson
2021-06-22 17:57 ` [PATCH 36/54] KVM: x86/mmu: Use MMU's role/role_regs to compute context's metadata Sean Christopherson
2021-06-22 17:57 ` [PATCH 37/54] KVM: x86/mmu: Use MMU's role to get EFER.NX during MMU configuration Sean Christopherson
2021-06-22 17:57 ` [PATCH 38/54] KVM: x86/mmu: Drop "nx" from MMU context now that there are no readers Sean Christopherson
2021-06-22 17:57 ` [PATCH 39/54] KVM: x86/mmu: Get nested MMU's root level from the MMU's role Sean Christopherson
2021-06-22 17:57 ` [PATCH 40/54] KVM: x86/mmu: Use MMU role_regs to get LA57, and drop vCPU LA57 helper Sean Christopherson
2021-06-22 17:57 ` [PATCH 41/54] KVM: x86/mmu: Consolidate reset_rsvds_bits_mask() calls Sean Christopherson
2021-06-23 20:07 ` Paolo Bonzini
2021-06-23 20:53 ` Sean Christopherson
2021-06-22 17:57 ` [PATCH 42/54] KVM: x86/mmu: Don't update nested guest's paging bitmasks if CR0.PG=0 Sean Christopherson
2021-06-22 17:57 ` [PATCH 43/54] KVM: x86/mmu: Add helper to update paging metadata Sean Christopherson
2021-06-22 17:57 ` [PATCH 44/54] KVM: x86/mmu: Add a helper to calculate root from role_regs Sean Christopherson
2021-06-22 17:57 ` [PATCH 45/54] KVM: x86/mmu: Collapse 32-bit PAE and 64-bit statements for helpers Sean Christopherson
2021-06-22 17:57 ` [PATCH 46/54] KVM: x86/mmu: Use MMU's role to determine PTTYPE Sean Christopherson
2021-06-22 17:57 ` [PATCH 47/54] KVM: x86/mmu: Add helpers to do full reserved SPTE checks w/ generic MMU Sean Christopherson
2021-06-23 20:13 ` Paolo Bonzini
2021-06-22 17:57 ` [PATCH 48/54] KVM: x86/mmu: WARN on any reserved SPTE value when making a valid SPTE Sean Christopherson
2021-06-22 17:57 ` [PATCH 49/54] KVM: x86: Enhance comments for MMU roles and nested transition trickiness Sean Christopherson
2021-06-22 17:57 ` [PATCH 50/54] KVM: x86/mmu: Optimize and clean up so called "last nonleaf level" logic Sean Christopherson
2021-06-23 20:22 ` Paolo Bonzini
2021-06-23 20:58 ` Sean Christopherson
2021-06-22 17:57 ` [PATCH 51/54] KVM: x86/mmu: Drop redundant rsvd bits reset for nested NPT Sean Christopherson
2021-06-22 17:57 ` [PATCH 52/54] KVM: x86/mmu: Get CR0.WP from MMU, not vCPU, in shadow page fault Sean Christopherson
2021-06-22 17:57 ` [PATCH 53/54] KVM: x86/mmu: Get CR4.SMEP " Sean Christopherson
2021-06-22 17:57 ` [PATCH 54/54] KVM: x86/mmu: Let guest use GBPAGES if supported in hardware and TDP is on Sean Christopherson
2021-06-23 20:29 ` [PATCH 00/54] KVM: x86/mmu: Bug fixes and summer cleaning Paolo Bonzini
2021-06-23 21:06 ` Sean Christopherson
2021-06-23 21:33 ` Paolo Bonzini
2021-06-23 22:08 ` Sean Christopherson
2021-06-23 22:12 ` Paolo Bonzini
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