From: Jiří Paleček jpalecek@web.de
[ Upstream commit 1cfff4d9a5d01fa61e5768a6afffc81ae1c8ecb9 ]
On AMD processors, in PAE 32bit mode, nested KVM instances don't work. The L0 host get a kernel OOPS, which is related to arch.mmu->pae_root being NULL.
The reason for this is that when setting up nested KVM instance, arch.mmu is set to &arch.guest_mmu (while normally, it would be &arch.root_mmu). However, the initialization and allocation of pae_root only creates it in root_mmu. KVM code (ie. in mmu_alloc_shadow_roots) then accesses arch.mmu->pae_root, which is the unallocated arch.guest_mmu->pae_root.
This fix just allocates (and frees) pae_root in both guest_mmu and root_mmu (and also lm_root if it was allocated). The allocation is subject to previous restrictions ie. it won't allocate anything on 64-bit and AFAIK not on Intel.
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=203923 Fixes: 14c07ad89f4d ("x86/kvm/mmu: introduce guest_mmu") Signed-off-by: Jiri Palecek jpalecek@web.de Tested-by: Jiri Palecek jpalecek@web.de Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/mmu.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 66055ca29b6b4..9130152d5ed83 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5607,13 +5607,13 @@ slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot, PT_PAGE_TABLE_LEVEL, lock_flush_tlb); }
-static void free_mmu_pages(struct kvm_vcpu *vcpu) +static void free_mmu_pages(struct kvm_mmu *mmu) { - free_page((unsigned long)vcpu->arch.mmu->pae_root); - free_page((unsigned long)vcpu->arch.mmu->lm_root); + free_page((unsigned long)mmu->pae_root); + free_page((unsigned long)mmu->lm_root); }
-static int alloc_mmu_pages(struct kvm_vcpu *vcpu) +static int alloc_mmu_pages(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) { struct page *page; int i; @@ -5634,9 +5634,9 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu) if (!page) return -ENOMEM;
- vcpu->arch.mmu->pae_root = page_address(page); + mmu->pae_root = page_address(page); for (i = 0; i < 4; ++i) - vcpu->arch.mmu->pae_root[i] = INVALID_PAGE; + mmu->pae_root[i] = INVALID_PAGE;
return 0; } @@ -5644,6 +5644,7 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu) int kvm_mmu_create(struct kvm_vcpu *vcpu) { uint i; + int ret;
vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; @@ -5661,7 +5662,19 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) vcpu->arch.guest_mmu.prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID;
vcpu->arch.nested_mmu.translate_gpa = translate_nested_gpa; - return alloc_mmu_pages(vcpu); + + ret = alloc_mmu_pages(vcpu, &vcpu->arch.guest_mmu); + if (ret) + return ret; + + ret = alloc_mmu_pages(vcpu, &vcpu->arch.root_mmu); + if (ret) + goto fail_allocate_root; + + return ret; + fail_allocate_root: + free_mmu_pages(&vcpu->arch.guest_mmu); + return ret; }
@@ -6134,7 +6147,8 @@ unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm) void kvm_mmu_destroy(struct kvm_vcpu *vcpu) { kvm_mmu_unload(vcpu); - free_mmu_pages(vcpu); + free_mmu_pages(&vcpu->arch.root_mmu); + free_mmu_pages(&vcpu->arch.guest_mmu); mmu_free_memory_caches(vcpu); }