[PATCH 15/15] KVM: X86: Always set gpte_is_8_bytes when direct map

Lai Jiangshan
2021-11-18T11:14:05Z

When direct map, gpte_is_8_bytes has no meaning, but it is true for all
other cases except direct map when nonpaping.

Setting gpte_is_8_bytes to true when nonpaping can ensure that
!gpte_is_8_bytes means 32-bit gptes for shadow paging.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
Documentation/virt/kvm/mmu.rst | 2 +-
arch/x86/kvm/mmu/mmu.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/virt/kvm/mmu.rst b/Documentation/virt/kvm/mmu.rst
index f60f5488e121..5d1086602759 100644
--- a/Documentation/virt/kvm/mmu.rst
+++ b/Documentation/virt/kvm/mmu.rst
@@ -179,7 +179,7 @@ Shadow pages contain the following information:
unpinned it will be destroyed.
role.gpte_is_8_bytes:
Reflects the size of the guest PTE for which the page is valid, i.e. '1'
- if 64-bit gptes are in use, '0' if 32-bit gptes are in use.
+ if direct map or 64-bit gptes are in use, '0' if 32-bit gptes are in use.
role.efer_nx:
Contains the value of efer.nx for which the page is valid.
role.cr0_wp:
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 6948f2d696c3..0c92cbc07320 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2083,7 +2083,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
role.level = level;
role.direct = direct;
role.access = access;
- if (!direct_mmu && !role.gpte_is_8_bytes) {
+ if (!role.gpte_is_8_bytes) {
quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
role.quadrant = quadrant;
@@ -4777,7 +4777,7 @@ kvm_calc_shadow_root_page_role_common(struct kvm_vcpu *vcpu,

role.base.smep_andnot_wp = role.ext.cr4_smep && !____is_cr0_wp(regs);
role.base.smap_andnot_wp = role.ext.cr4_smap && !____is_cr0_wp(regs);
- role.base.gpte_is_8_bytes = ____is_cr0_pg(regs) && ____is_cr4_pae(regs);
+ role.base.gpte_is_8_bytes = !____is_cr0_pg(regs) || ____is_cr4_pae(regs);

return role;
}
--
2.19.1.6.gb485710b