linux-kernel - [PATCH v12 38/84] KVM: x86/mmu: Put direct prefetched pages via kvm_release_page

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Message-ID: <20240726235234.228822-39-seanjc@google.com>
Date: Fri, 26 Jul 2024 16:51:47 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Tianrui Zhao <zhaotianrui@...ngson.cn>, 
	Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>, 
	Michael Ellerman <mpe@...erman.id.au>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>, 
	Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	David Matlack <dmatlack@...gle.com>, David Stevens <stevensd@...omium.org>
Subject: [PATCH v12 38/84] KVM: x86/mmu: Put direct prefetched pages via kvm_release_page_clean()

Use kvm_release_page_clean() to put prefeteched pages instead of calling
put_page() directly.  This will allow de-duplicating the prefetch code
between indirect and direct MMUs.

Note, there's a small functional change as kvm_release_page_clean() marks
the page/folio as accessed.  While it's not strictly guaranteed that the
guest will access the page, KVM won't intercept guest accesses, i.e. won't
mark the page accessed if it _is_ accessed by the guest (unless A/D bits
are disabled, but running without A/D bits is effectively limited to
pre-HSW Intel CPUs).

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4d30920f653d..0def1444c01c 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2919,7 +2919,7 @@ static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu,
 	for (i = 0; i < ret; i++, gfn++, start++) {
 		mmu_set_spte(vcpu, slot, start, access, gfn,
 			     page_to_pfn(pages[i]), NULL);
-		put_page(pages[i]);
+		kvm_release_page_clean(pages[i]);
 	}
 
 	return 0;
-- 
2.46.0.rc1.232.g9752f9e123-goog