From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Mingwei Zhang <mizhang@google.com>,
David Matlack <dmatlack@google.com>,
Jim Mattson <jmattson@google.com>
Subject: [PATCH v3 05/12] KVM: x86/mmu: Cleanup sanity check of SPTEs at SP free
Date: Fri, 28 Jul 2023 17:47:15 -0700 [thread overview]
Message-ID: <20230729004722.1056172-6-seanjc@google.com> (raw)
In-Reply-To: <20230729004722.1056172-1-seanjc@google.com>
Massage the error message for the sanity check on SPTEs when freeing a
shadow page to be more verbose, and to print out all shadow-present SPTEs,
not just the first SPTE encountered. Printing all SPTEs can be quite
valuable for debug, e.g. highlights whether the leak is a one-off or
widepsread, or possibly the result of memory corruption (something else
in the kernel stomping on KVM's SPTEs).
Opportunistically move the MMU_WARN_ON() into the helper itself, which
will allow a future cleanup to use BUILD_BUG_ON_INVALID() as the stub for
MMU_WARN_ON(). BUILD_BUG_ON_INVALID() works as intended and results in
the compiler complaining about is_empty_shadow_page() not being declared.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/mmu.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 08d08f34e6a3..8a21b06a9646 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1693,21 +1693,19 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
return young;
}
+static void kvm_mmu_check_sptes_at_free(struct kvm_mmu_page *sp)
+{
#ifdef MMU_DEBUG
-static int is_empty_shadow_page(u64 *spt)
-{
int i;
for (i = 0; i < SPTE_ENT_PER_PAGE; i++) {
- if (is_shadow_present_pte(spt[i])) {
- printk(KERN_ERR "%s: %p %llx\n", __func__,
- &spt[i], spt[i]);
- return 0;
- }
+ if (MMU_WARN_ON(is_shadow_present_pte(sp->spt[i])))
+ pr_err_ratelimited("SPTE %llx (@ %p) for gfn %llx shadow-present at free",
+ sp->spt[i], &sp->spt[i],
+ kvm_mmu_page_get_gfn(sp, i));
}
- return 1;
-}
#endif
+}
/*
* This value is the sum of all of the kvm instances's
@@ -1735,7 +1733,8 @@ static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp)
{
- MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
+ kvm_mmu_check_sptes_at_free(sp);
+
hlist_del(&sp->hash_link);
list_del(&sp->link);
free_page((unsigned long)sp->spt);
--
2.41.0.487.g6d72f3e995-goog
next prev parent reply other threads:[~2023-07-29 0:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-29 0:47 [PATCH v3 00/12] KVM: x86/mmu: Clean up MMU_DEBUG and BUG/WARN usage Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 01/12] KVM: x86/mmu: Delete pgprintk() and all its usage Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 02/12] KVM: x86/mmu: Delete rmap_printk() " Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 03/12] KVM: x86/mmu: Delete the "dbg" module param Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 04/12] KVM: x86/mmu: Avoid pointer arithmetic when iterating over SPTEs Sean Christopherson
2023-08-01 14:06 ` Philippe Mathieu-Daudé
2023-07-29 0:47 ` Sean Christopherson [this message]
2023-07-29 0:47 ` [PATCH v3 06/12] KVM: x86/mmu: Rename MMU_WARN_ON() to KVM_MMU_WARN_ON() Sean Christopherson
2023-08-01 14:02 ` Philippe Mathieu-Daudé
2023-07-29 0:47 ` [PATCH v3 07/12] KVM: x86/mmu: Convert "runtime" WARN_ON() assertions to WARN_ON_ONCE() Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 08/12] KVM: x86/mmu: Bug the VM if a vCPU ends up in long mode without PAE enabled Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 09/12] KVM: x86/mmu: Replace MMU_DEBUG with proper KVM_PROVE_MMU Kconfig Sean Christopherson
2023-08-01 14:02 ` Philippe Mathieu-Daudé
2023-07-29 0:47 ` [PATCH v3 10/12] KVM: x86/mmu: Use BUILD_BUG_ON_INVALID() for KVM_MMU_WARN_ON() stub Sean Christopherson
2023-08-01 14:04 ` Philippe Mathieu-Daudé
2023-08-01 23:41 ` Sean Christopherson
2023-08-02 6:49 ` Philippe Mathieu-Daudé
2023-07-29 0:47 ` [PATCH v3 11/12] KVM: x86/mmu: Plumb "struct kvm" all the way to pte_list_remove() Sean Christopherson
2023-07-29 0:47 ` [PATCH v3 12/12] KVM: x86/mmu: BUG() in rmap helpers iff CONFIG_BUG_ON_DATA_CORRUPTION=y Sean Christopherson
2023-08-04 0:41 ` [PATCH v3 00/12] KVM: x86/mmu: Clean up MMU_DEBUG and BUG/WARN usage Sean Christopherson
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