mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Lai Jiangshan <jiangshan.ljs@antgroup.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	kvm@vger.kernel.org
Subject: [PATCH] kvm: x86/mmu: Don't clear write flooding for direct SP
Date: Thu,  5 Jan 2023 18:03:10 +0800	[thread overview]
Message-ID: <20230105100310.6700-1-jiangshanlai@gmail.com> (raw)

From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

Although there is no harm, but there is no point to clear write
flooding for direct SP.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
 arch/x86/kvm/mmu/paging_tmpl.h | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 79da423ee4cb..11f17efbec97 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -649,12 +649,12 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
 	if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root.hpa)))
 		goto out_gpte_changed;
 
-	for (shadow_walk_init(&it, vcpu, fault->addr);
-	     shadow_walk_okay(&it) && it.level > gw->level;
-	     shadow_walk_next(&it)) {
+	for_each_shadow_entry(vcpu, fault->addr, it) {
 		gfn_t table_gfn;
 
 		clear_sp_write_flooding_count(it.sptep);
+		if (it.level == gw->level)
+			break;
 
 		table_gfn = gw->table_gfn[it.level - 2];
 		access = gw->pt_access[it.level - 2];
@@ -706,8 +706,6 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
 	trace_kvm_mmu_spte_requested(fault);
 
 	for (; shadow_walk_okay(&it); shadow_walk_next(&it)) {
-		clear_sp_write_flooding_count(it.sptep);
-
 		/*
 		 * We cannot overwrite existing page tables with an NX
 		 * large page, as the leaf could be executable.
-- 
2.19.1.6.gb485710b


             reply	other threads:[~2023-01-05 10:03 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-05 10:03 Lai Jiangshan [this message]
2023-01-19 20:54 ` Sean Christopherson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230105100310.6700-1-jiangshanlai@gmail.com \
    --to=jiangshanlai@gmail.com \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=jiangshan.ljs@antgroup.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=seanjc@google.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®