lkml.org 
[lkml]   [2021]   [Feb]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH 21/24] KVM: x86/mmu: Tweak auditing WARN for A/D bits to !PRESENT (was MMIO)
From
Tweak the MMU_WARN that guards against weirdness when querying A/D status
to fire on a !MMU_PRESENT SPTE, as opposed to a MMIO SPTE. Attempting to
query A/D status on any kind of !MMU_PRESENT SPTE, MMIO or otherwise,
indicates a KVM bug. Case in point, several now-fixed bugs were
identified by enabling this new WARN.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/spte.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 645e9bc2d4a2..2fad4ccd3679 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -209,6 +209,11 @@ static inline bool is_mmio_spte(u64 spte)
likely(shadow_mmio_value);
}

+static inline bool is_shadow_present_pte(u64 pte)
+{
+ return !!(pte & SPTE_MMU_PRESENT_MASK);
+}
+
static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
{
return sp->role.ad_disabled;
@@ -216,13 +221,13 @@ static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)

static inline bool spte_ad_enabled(u64 spte)
{
- MMU_WARN_ON(is_mmio_spte(spte));
+ MMU_WARN_ON(!is_shadow_present_pte(spte));
return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_DISABLED_MASK;
}

static inline bool spte_ad_need_write_protect(u64 spte)
{
- MMU_WARN_ON(is_mmio_spte(spte));
+ MMU_WARN_ON(!is_shadow_present_pte(spte));
/*
* This is benign for non-TDP SPTEs as SPTE_TDP_AD_ENABLED_MASK is '0',
* and non-TDP SPTEs will never set these bits. Optimize for 64-bit
@@ -233,13 +238,13 @@ static inline bool spte_ad_need_write_protect(u64 spte)

static inline u64 spte_shadow_accessed_mask(u64 spte)
{
- MMU_WARN_ON(is_mmio_spte(spte));
+ MMU_WARN_ON(!is_shadow_present_pte(spte));
return spte_ad_enabled(spte) ? shadow_accessed_mask : 0;
}

static inline u64 spte_shadow_dirty_mask(u64 spte)
{
- MMU_WARN_ON(is_mmio_spte(spte));
+ MMU_WARN_ON(!is_shadow_present_pte(spte));
return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
}

@@ -248,11 +253,6 @@ static inline bool is_access_track_spte(u64 spte)
return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
}

-static inline bool is_shadow_present_pte(u64 pte)
-{
- return !!(pte & SPTE_MMU_PRESENT_MASK);
-}
-
static inline bool is_large_pte(u64 pte)
{
return pte & PT_PAGE_SIZE_MASK;
--
2.30.1.766.gb4fecdf3b7-goog
\
 
 \ /
  Last update: 2021-02-25 22:04    [W:0.179 / U:0.824 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site