Use the calculated role as-is when propagating it to kvm_mmu.mmu_role,
i.e. stop masking off meaningful fields. The concept of masking off
fields came from kvm_mmu_pte_write(), which (correctly) ignores certain
fields when comparing kvm_mmu_page.role against kvm_mmu.mmu_role, e.g.
the current mmu's access and level have no relation to a shadow page's
access and level.
This fixes a bug where KVM will fail to reset shadow_root_level and
root_level when L1 switches from running L2 with 5-level to running L2
with 4-level.
Opportunistically rework the mask for kvm_mmu_pte_write() to define the
fields that should be ignored as opposed to the fields that should be
checked, i.e. make it opt-out instead of opt-in so that new fields are
automatically picked up. While doing so, stop ignoring "direct". The
field is effectively ignored anyways because kvm_mmu_pte_write() is only
reached with an indirect mmu and the loop only walks indirect shadow
pages, but double checking "direct" literally costs nothing.
Fixes: 9fa72119b24d ("kvm: x86: Introduce kvm_mmu_calc_root_page_role()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c4e0b97f82ac..80b21b7cf092 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -215,17 +215,6 @@ struct kvm_shadow_walk_iterator {
unsigned index;
};
-static const union kvm_mmu_page_role mmu_base_role_mask = {
- .cr0_wp = 1,
- .gpte_is_8_bytes = 1,
- .nxe = 1,
- .smep_andnot_wp = 1,
- .smap_andnot_wp = 1,
- .smm = 1,
- .guest_mode = 1,
- .ad_disabled = 1,
-};
-
#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \
for (shadow_walk_init_using_root(&(_walker), (_vcpu), \
(_root), (_addr)); \
@@ -4919,7 +4908,6 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
union kvm_mmu_role new_role =
kvm_calc_tdp_mmu_root_page_role(vcpu, false);
- new_role.base.word &= mmu_base_role_mask.word;
if (new_role.as_u64 == context->mmu_role.as_u64)
return;
@@ -4991,7 +4979,6 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
union kvm_mmu_role new_role =
kvm_calc_shadow_mmu_root_page_role(vcpu, false);
- new_role.base.word &= mmu_base_role_mask.word;
if (new_role.as_u64 == context->mmu_role.as_u64)
return;
@@ -5048,7 +5035,6 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
__kvm_mmu_new_cr3(vcpu, new_eptp, new_role.base, false);
- new_role.base.word &= mmu_base_role_mask.word;
if (new_role.as_u64 == context->mmu_role.as_u64)
return;
@@ -5089,7 +5075,6 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
union kvm_mmu_role new_role = kvm_calc_mmu_role_common(vcpu, false);
struct kvm_mmu *g_context = &vcpu->arch.nested_mmu;
- new_role.base.word &= mmu_base_role_mask.word;
if (new_role.as_u64 == g_context->mmu_role.as_u64)
return;
@@ -5328,6 +5313,22 @@ static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte)
return spte;
}
+/*
+ * Ignore various flags when determining if a SPTE can be immediately
+ * overwritten for the current MMU.
+ * - level: explicitly checked in mmu_pte_write_new_pte(), and will never
+ * match the current MMU role, as MMU's level tracks the root level.
+ * - access: updated based on the new guest PTE
+ * - quadrant: handled by get_written_sptes()
+ * - invalid: always false (loop only walks valid shadow pages)
+ */
+static const union kvm_mmu_page_role role_ign = {
+ .level = 0xf,
+ .access = 0x7,
+ .quadrant = 0x3,
+ .invalid = 0x1,
+};
+
static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes,
struct kvm_page_track_notifier_node *node)
@@ -5383,8 +5384,8 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
entry = *spte;
mmu_page_zap_pte(vcpu->kvm, sp, spte);
if (gentry &&
- !((sp->role.word ^ base_role)
- & mmu_base_role_mask.word) && rmap_can_add(vcpu))
+ !((sp->role.word ^ base_role) & ~role_ign.word) &&
+ rmap_can_add(vcpu))
mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
if (need_remote_flush(entry, *spte))
remote_flush = true;
--
2.24.1
