linux-kernel - [PATCH v12 05/84] KVM: Add kvm_release_page_unused() API to put pages that KVM never consumes

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Message-ID: <20240726235234.228822-6-seanjc@google.com>
Date: Fri, 26 Jul 2024 16:51:14 -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 05/84] KVM: Add kvm_release_page_unused() API to put pages
 that KVM never consumes

Add an API to release an unused page, i.e. to put a page without marking
it accessed or dirty.  The API will be used when KVM faults-in a page but
bails before installing the guest mapping (and other similar flows).

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 include/linux/kvm_host.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3d9617d1de41..c5d39a337aa3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1201,6 +1201,15 @@ unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable);
 unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn);
 unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn,
 				      bool *writable);
+
+static inline void kvm_release_page_unused(struct page *page)
+{
+	if (!page)
+		return;
+
+	put_page(page);
+}
+
 void kvm_release_page_clean(struct page *page);
 void kvm_release_page_dirty(struct page *page);
 
-- 
2.46.0.rc1.232.g9752f9e123-goog