linux-kernel - [RFC PATCH 4/6] KVM: arm64: Optimize TLBIs in the dirty logging path

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Message-ID: <20230109215347.3119271-5-rananta@google.com>
Date:   Mon,  9 Jan 2023 21:53:45 +0000
From:   Raghavendra Rao Ananta <rananta@...gle.com>
To:     Oliver Upton <oupton@...gle.com>, Marc Zyngier <maz@...nel.org>,
        Ricardo Koller <ricarkol@...gle.com>,
        Reiji Watanabe <reijiw@...gle.com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Jing Zhang <jingzhangos@...gle.com>,
        Colton Lewis <coltonlewis@...gle.com>,
        Raghavendra Rao Anata <rananta@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [RFC PATCH 4/6] KVM: arm64: Optimize TLBIs in the dirty logging path

Currently the dirty-logging paths, including
kvm_arch_flush_remote_tlbs_memslot() and kvm_mmu_wp_memory_region()
ivalidates the entire VM's TLB entries using kvm_flush_remote_tlbs().
As the range of IPAs is provided by these functions, this is highly
inefficient on the systems which support FEAT_TLBIRANGE. Hence,
use kvm_flush_remote_tlbs_range() to flush the TLBs instead.

Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
---
 arch/arm64/kvm/arm.c | 7 ++++++-
 arch/arm64/kvm/mmu.c | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 00da570ed72bd..179520888c697 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1433,7 +1433,12 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
 					const struct kvm_memory_slot *memslot)
 {
-	kvm_flush_remote_tlbs(kvm);
+	phys_addr_t start, end;
+
+	start = memslot->base_gfn << PAGE_SHIFT;
+	end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
+
+	kvm_flush_remote_tlbs_range(kvm, start, end);
 }
 
 static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 70f76bc909c5d..e34b81f5922ce 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -976,7 +976,7 @@ static void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
 	write_lock(&kvm->mmu_lock);
 	stage2_wp_range(&kvm->arch.mmu, start, end);
 	write_unlock(&kvm->mmu_lock);
-	kvm_flush_remote_tlbs(kvm);
+	kvm_flush_remote_tlbs_range(kvm, start, end);
 }
 
 /**
-- 
2.39.0.314.g84b9a713c41-goog