linux-kernel - [PATCH 06/15] KVM: x86/mmu: Implement PWALK_SET

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Message-ID: <20240910152207.38974-7-nikwip@amazon.de>
Date: Tue, 10 Sep 2024 15:21:58 +0000
From: Nikolas Wipper <nikwip@...zon.de>
To: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson
	<seanjc@...gle.com>, Vitaly Kuznetsov <vkuznets@...hat.com>
CC: Nicolas Saenz Julienne <nsaenz@...zon.com>, Alexander Graf
	<graf@...zon.de>, James Gowans <jgowans@...zon.com>,
	<nh-open-source@...zon.com>, Thomas Gleixner <tglx@...utronix.de>, "Ingo
 Molnar" <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, <linux-kernel@...r.kernel.org>,
	<kvm@...r.kernel.org>, <x86@...nel.org>, <linux-doc@...r.kernel.org>,
	<linux-kselftest@...r.kernel.org>, <kvmarm@...ts.linux.dev>,
	<kvm-riscv@...ts.infradead.org>, Nikolas Wipper <nikwip@...zon.de>
Subject: [PATCH 06/15] KVM: x86/mmu: Implement PWALK_SET_ACCESSED in page walker

Implement PWALK_SET_ACCESSED in the page walker. This flag allows
controling whether the page walker will set the accessed bits after a
successful page walk in all page table levels. If the page walk is aborted
for any reason, none of the access bits are set.

Signed-off-by: Nikolas Wipper <nikwip@...zon.de>
---
 arch/x86/kvm/mmu/paging_tmpl.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index c278b83b023f..eed6e2c653ba 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -317,6 +317,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 	const int write_fault = access & PFERR_WRITE_MASK;
 	const int user_fault  = access & PFERR_USER_MASK;
 	const int fetch_fault = access & PFERR_FETCH_MASK;
+	const int set_accessed = flags & PWALK_SET_ACCESSED;
 	u16 errcode = 0;
 	gpa_t real_gpa;
 	gfn_t gfn;
@@ -468,7 +469,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 		accessed_dirty &= pte >>
 			(PT_GUEST_DIRTY_SHIFT - PT_GUEST_ACCESSED_SHIFT);
 
-	if (unlikely(!accessed_dirty)) {
+	if (unlikely(set_accessed && !accessed_dirty)) {
 		ret = FNAME(update_accessed_dirty_bits)(vcpu, mmu, walker, addr,
 							write_fault);
 		if (unlikely(ret < 0))
-- 
2.40.1




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