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@xxxxxxxxxx>
---
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
