From: Anthony Yznaga <anthony.yznaga@oracle.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: pbonzini@redhat.com, sean.j.christopherson@intel.com,
vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com,
joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, hpa@zytor.com,
steven.sistare@oracle.com, anthony.yznaga@oracle.com
Subject: [PATCH 1/3] KVM: x86: remove unnecessary rmap walk of read-only memslots
Date: Tue, 2 Jun 2020 13:07:28 -0700 [thread overview]
Message-ID: <1591128450-11977-2-git-send-email-anthony.yznaga@oracle.com> (raw)
In-Reply-To: <1591128450-11977-1-git-send-email-anthony.yznaga@oracle.com>
There's no write access to remove. An existing memslot cannot be updated
to set or clear KVM_MEM_READONLY, and any mappings established in a newly
created or moved read-only memslot will already be read-only.
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
arch/x86/kvm/x86.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c17e6eb9ad43..23fd888e52ee 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10038,11 +10038,9 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
struct kvm_memory_slot *new)
{
- /* Still write protect RO slot */
- if (new->flags & KVM_MEM_READONLY) {
- kvm_mmu_slot_remove_write_access(kvm, new, PT_PAGE_TABLE_LEVEL);
+ /* Nothing to do for RO slots */
+ if (new->flags & KVM_MEM_READONLY)
return;
- }
/*
* Call kvm_x86_ops dirty logging hooks when they are valid.
--
2.13.3
next prev parent reply other threads:[~2020-06-02 20:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 20:07 [PATCH 0/3] avoid unnecessary memslot rmap walks Anthony Yznaga
2020-06-02 20:07 ` Anthony Yznaga [this message]
2020-06-02 20:07 ` [PATCH 2/3] KVM: x86: avoid unnecessary rmap walks when creating/moving slots Anthony Yznaga
2020-06-02 20:07 ` [PATCH 3/3] KVM: x86: minor code refactor and comments fixup around dirty logging Anthony Yznaga
2020-06-04 18:42 ` [PATCH 0/3] avoid unnecessary memslot rmap walks Paolo Bonzini
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