linux-kernel - [RFC PATCH v3 35/59] KVM: x86/mmu: Return old SPTE from mmu_spte_clear_track

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Date:   Wed, 24 Nov 2021 16:20:18 -0800
From:   isaku.yamahata@...el.com
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [RFC PATCH v3 35/59] KVM: x86/mmu: Return old SPTE from mmu_spte_clear_track_bits()

From: Sean Christopherson <sean.j.christopherson@...el.com>

Return the old SPTE when clearing a SPTE and push the "old SPTE present"
check to the caller.  Private shadow page support will use the old SPTE
in rmap_remove() to determine whether or not there is a linked private
shadow page.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.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 510991c2e94e..f1bd7d952bfe 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -616,7 +616,7 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte)
  * state bits, it is used to clear the last level sptep.
  * Returns the old PTE.
  */
-static int mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep)
+static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep)
 {
 	kvm_pfn_t pfn;
 	u64 old_spte = *sptep;
-- 
2.25.1