[PATCH 5.15 160/207] KVM: X86: Fix when shadow_root_level=5 && guest root_level<4

Greg Kroah-Hartman
2021-12-06T15:59:57Z

From: Lai Jiangshan <laijs@linux.alibaba.com>

[ Upstream commit 12ec33a705749e18d9588b0a0e69e02821371156 ]

If the is an L1 with nNPT in 32bit, the shadow walk starts with
pae_root.

Fixes: a717a780fc4e ("KVM: x86/mmu: Support shadowing NPT when 5-level paging is enabled in host)
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/mmu/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c9b1d63d3cfba..287fc1086db78 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2188,10 +2188,10 @@ static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterato
iterator->shadow_addr = root;
iterator->level = vcpu->arch.mmu->shadow_root_level;

- if (iterator->level == PT64_ROOT_4LEVEL &&
+ if (iterator->level >= PT64_ROOT_4LEVEL &&
vcpu->arch.mmu->root_level < PT64_ROOT_4LEVEL &&
!vcpu->arch.mmu->direct_map)
- --iterator->level;
+ iterator->level = PT32E_ROOT_LEVEL;

if (iterator->level == PT32E_ROOT_LEVEL) {
/*
--
2.33.0