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Message-Id: <4bdb2c587d917a67eecbae6f02926c31c32e3e39.1605232743.git.isaku.yamahata@intel.com>
Date: Mon, 16 Nov 2020 10:26:25 -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>, x86@...nel.org,
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 40/67] 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>
---
arch/x86/kvm/mmu/mmu.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 25aafac9b5de..8d847c3abf1d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -552,9 +552,9 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte)
* Rules for using mmu_spte_clear_track_bits:
* It sets the sptep from present to nonpresent, and track the
* state bits, it is used to clear the last level sptep.
- * Returns non-zero if the PTE was previously valid.
+ * Returns the old PTE.
*/
-static int mmu_spte_clear_track_bits(u64 *sptep)
+static u64 mmu_spte_clear_track_bits(u64 *sptep)
{
kvm_pfn_t pfn;
u64 old_spte = *sptep;
@@ -565,7 +565,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
old_spte = __update_clear_spte_slow(sptep, shadow_init_value);
if (!is_shadow_present_pte(old_spte))
- return 0;
+ return old_spte;
pfn = spte_to_pfn(old_spte);
@@ -582,7 +582,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
if (is_dirty_spte(old_spte))
kvm_set_pfn_dirty(pfn);
- return 1;
+ return old_spte;
}
/*
@@ -1113,7 +1113,9 @@ static u64 *rmap_get_next(struct rmap_iterator *iter)
static void drop_spte(struct kvm *kvm, u64 *sptep)
{
- if (mmu_spte_clear_track_bits(sptep))
+ u64 old_spte = mmu_spte_clear_track_bits(sptep);
+
+ if (is_shadow_present_pte(old_spte))
rmap_remove(kvm, sptep);
}
--
2.17.1
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