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Message-ID: <20240724011037.3671523-10-jthoughton@google.com>
Date: Wed, 24 Jul 2024 01:10:34 +0000
From: James Houghton <jthoughton@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>, Paolo Bonzini <pbonzini@...hat.com>
Cc: Ankit Agrawal <ankita@...dia.com>, Axel Rasmussen <axelrasmussen@...gle.com>,
Catalin Marinas <catalin.marinas@....com>, David Matlack <dmatlack@...gle.com>,
David Rientjes <rientjes@...gle.com>, James Houghton <jthoughton@...gle.com>,
James Morse <james.morse@....com>, Jason Gunthorpe <jgg@...pe.ca>, Jonathan Corbet <corbet@....net>,
Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
Raghavendra Rao Ananta <rananta@...gle.com>, Ryan Roberts <ryan.roberts@....com>,
Sean Christopherson <seanjc@...gle.com>, Shaoqin Huang <shahuang@...hat.com>,
Suzuki K Poulose <suzuki.poulose@....com>, Wei Xu <weixugc@...gle.com>,
Will Deacon <will@...nel.org>, Yu Zhao <yuzhao@...gle.com>, Zenghui Yu <yuzenghui@...wei.com>,
kvmarm@...ts.linux.dev, kvm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v6 09/11] KVM: x86: Implement fast_only versions of kvm_{test_,}age_gfn
These fast-only versions simply ignore the shadow MMU. We can locklessly
handle the shadow MMU later.
Set HAVE_KVM_MMU_NOTIFIER_YOUNG_FAST_ONLY for X86_64 only, as that is
the only case where the TDP MMU might be used. Without the TDP MMU, the
fast-only notifiers will always be no-ops. It would be ideal not to
report has_fast_only if !tdp_mmu_enabled, but tdp_mmu_enabled can be
changed at any time.
Signed-off-by: James Houghton <jthoughton@...gle.com>
---
arch/x86/kvm/Kconfig | 1 +
arch/x86/kvm/mmu/mmu.c | 4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 6ac43074c5e9..ed9049cf1255 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -24,6 +24,7 @@ config KVM
select KVM_COMMON
select KVM_GENERIC_MMU_NOTIFIER
select KVM_MMU_NOTIFIER_YOUNG_LOCKLESS
+ select HAVE_KVM_MMU_NOTIFIER_YOUNG_FAST_ONLY if X86_64
select HAVE_KVM_IRQCHIP
select HAVE_KVM_PFNCACHE
select HAVE_KVM_DIRTY_RING_TSO
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 919d59385f89..3c6c9442434a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1641,7 +1641,7 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
if (tdp_mmu_enabled)
young |= kvm_tdp_mmu_age_gfn_range(kvm, range);
- if (kvm_has_shadow_mmu_sptes(kvm)) {
+ if (!range->arg.fast_only && kvm_has_shadow_mmu_sptes(kvm)) {
write_lock(&kvm->mmu_lock);
young = kvm_handle_gfn_range(kvm, range, kvm_age_rmap);
write_unlock(&kvm->mmu_lock);
@@ -1657,7 +1657,7 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
if (tdp_mmu_enabled)
young |= kvm_tdp_mmu_test_age_gfn(kvm, range);
- if (!young && kvm_has_shadow_mmu_sptes(kvm)) {
+ if (!young && !range->arg.fast_only && kvm_has_shadow_mmu_sptes(kvm)) {
write_lock(&kvm->mmu_lock);
young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmap);
write_unlock(&kvm->mmu_lock);
--
2.46.0.rc1.232.g9752f9e123-goog
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