linux-kernel - [PATCH 2/5] KVM: x86/mmu: WARN if TDP MMU's set_tdp

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Message-Id: <20210226010329.1766033-3-seanjc@google.com>
Date:   Thu, 25 Feb 2021 17:03:26 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 2/5] KVM: x86/mmu: WARN if TDP MMU's set_tdp_spte() sees
 multiple GFNs

WARN if set_tdp_spte() is invoked with multipel GFNs.  It is specifically
a callback to handle a single host PTE being changed.  Consuming the
@end parameter also eliminates the confusing 'unused' parameter.

Cc: Ben Gardon <bgardon@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 3290e53fb850..020f2e573f44 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1022,7 +1022,7 @@ int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva)
  * Returns non-zero if a flush is needed before releasing the MMU lock.
  */
 static int set_tdp_spte(struct kvm *kvm, struct kvm_memory_slot *slot,
-			struct kvm_mmu_page *root, gfn_t gfn, gfn_t unused,
+			struct kvm_mmu_page *root, gfn_t gfn, gfn_t end,
 			unsigned long data)
 {
 	struct tdp_iter iter;
@@ -1033,7 +1033,7 @@ static int set_tdp_spte(struct kvm *kvm, struct kvm_memory_slot *slot,
 
 	rcu_read_lock();
 
-	WARN_ON(pte_huge(*ptep));
+	WARN_ON(pte_huge(*ptep) || (gfn + 1) != end);
 
 	new_pfn = pte_pfn(*ptep);
 
-- 
2.30.1.766.gb4fecdf3b7-goog