[v3,09/12] KVM: x86/mmu: Replace MMU_DEBUG with proper KVM_PROVE_MMU Kconfig
Commit Message
Replace MMU_DEBUG, which requires manually modifying KVM to enable the
macro, with a proper Kconfig, KVM_PROVE_MMU. Now that pgprintk() and
rmap_printk() are gone, i.e. the macro guards only KVM_MMU_WARN_ON() and
won't flood the kernel logs, enabling the option for debug kernels is both
desirable and feasible.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/Kconfig | 13 +++++++++++++
arch/x86/kvm/mmu/mmu.c | 2 +-
arch/x86/kvm/mmu/mmu_internal.h | 4 +---
3 files changed, 15 insertions(+), 4 deletions(-)
Comments
On 29/7/23 02:47, Sean Christopherson wrote:
> Replace MMU_DEBUG, which requires manually modifying KVM to enable the
> macro, with a proper Kconfig, KVM_PROVE_MMU. Now that pgprintk() and
> rmap_printk() are gone, i.e. the macro guards only KVM_MMU_WARN_ON() and
> won't flood the kernel logs, enabling the option for debug kernels is both
> desirable and feasible.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/Kconfig | 13 +++++++++++++
> arch/x86/kvm/mmu/mmu.c | 2 +-
> arch/x86/kvm/mmu/mmu_internal.h | 4 +---
> 3 files changed, 15 insertions(+), 4 deletions(-)
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
@@ -138,6 +138,19 @@ config KVM_XEN
If in doubt, say "N".
+config KVM_PROVE_MMU
+ bool "Prove KVM MMU correctness"
+ depends on DEBUG_KERNEL
+ depends on KVM
+ depends on EXPERT
+ help
+ Enables runtime assertions in KVM's MMU that are too costly to enable
+ in anything remotely resembling a production environment, e.g. this
+ gates code that verifies a to-be-freed page table doesn't have any
+ present SPTEs.
+
+ If in doubt, say "N".
+
config KVM_EXTERNAL_WRITE_TRACKING
bool
@@ -1695,7 +1695,7 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
static void kvm_mmu_check_sptes_at_free(struct kvm_mmu_page *sp)
{
-#ifdef MMU_DEBUG
+#ifdef CONFIG_KVM_PROVE_MMU
int i;
for (i = 0; i < SPTE_ENT_PER_PAGE; i++) {
@@ -6,9 +6,7 @@
#include <linux/kvm_host.h>
#include <asm/kvm_host.h>
-#undef MMU_DEBUG
-
-#ifdef MMU_DEBUG
+#ifdef CONFIG_KVM_PROVE_MMU
#define KVM_MMU_WARN_ON(x) WARN_ON_ONCE(x)
#else
#define KVM_MMU_WARN_ON(x) do { } while (0)