KVM: x86/mmu: Sanity check input to kvm_mmu_free_roots()

Tweak KVM_MMU_ROOTS_ALL to precisely cover all current+previous root
flags, and add a sanity in kvm_mmu_free_roots() to verify that the set
of roots to free doesn't stray outside KVM_MMU_ROOTS_ALL.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-8-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b7526c1..c23c49e 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -420,6 +420,10 @@ struct kvm_mmu_root_info {
 
 #define KVM_MMU_NUM_PREV_ROOTS 3
 
+#define KVM_MMU_ROOT_CURRENT           BIT(0)
+#define KVM_MMU_ROOT_PREVIOUS(i)       BIT(1+i)
+#define KVM_MMU_ROOTS_ALL              (BIT(1 + KVM_MMU_NUM_PREV_ROOTS) - 1)
+
 #define KVM_HAVE_MMU_RWLOCK
 
 struct kvm_mmu_page;
@@ -1997,10 +2001,6 @@ static inline int __kvm_irq_line_state(unsigned long *irq_state,
        return !!(*irq_state);
 }
 
-#define KVM_MMU_ROOT_CURRENT           BIT(0)
-#define KVM_MMU_ROOT_PREVIOUS(i)       BIT(1+i)
-#define KVM_MMU_ROOTS_ALL              (~0UL)
-
 int kvm_pic_set_irq(struct kvm_pic *pic, int irq, int irq_source_id, int level);
 void kvm_pic_clear_all(struct kvm_pic *pic, int irq_source_id);
 

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cb01e01..ffc18f5 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3568,6 +3568,8 @@ void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu,
        LIST_HEAD(invalid_list);
        bool free_active_root;
 
+       WARN_ON_ONCE(roots_to_free & ~KVM_MMU_ROOTS_ALL);
+
        BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG);
 
        /* Before acquiring the MMU lock, see if we need to do any real work. */