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authorNikunj A Dadhania <nikunj@amd.com>2022-01-05 09:33:37 +0530
committerPaolo Bonzini <pbonzini@redhat.com>2022-01-07 12:04:01 -0500
commitfffb5323780786c81ba005f8b8603d4a558aad28 (patch)
treea3e1662cef3912b0dcbc4a08ed920fe5fabf9b2f /arch
parent597cb7968cb6243e915ba9599195656be14773e5 (diff)
KVM: x86: Check for rmaps allocation
With TDP MMU being the default now, access to mmu_rmaps_stat debugfs file causes following oops: BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 3185 Comm: cat Not tainted 5.16.0-rc4+ #204 RIP: 0010:pte_list_count+0x6/0x40 Call Trace: <TASK> ? kvm_mmu_rmaps_stat_show+0x15e/0x320 seq_read_iter+0x126/0x4b0 ? aa_file_perm+0x124/0x490 seq_read+0xf5/0x140 full_proxy_read+0x5c/0x80 vfs_read+0x9f/0x1a0 ksys_read+0x67/0xe0 __x64_sys_read+0x19/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fca6fc13912 Return early when rmaps are not present. Reported-by: Vasant Hegde <vasant.hegde@amd.com> Tested-by: Vasant Hegde <vasant.hegde@amd.com> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220105040337.4234-1-nikunj@amd.com> Cc: stable@vger.kernel.org Fixes: 3bcd0662d66f ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/debugfs.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index 54a83a744538..f33c804a922a 100644
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -95,6 +95,9 @@ static int kvm_mmu_rmaps_stat_show(struct seq_file *m, void *v)
unsigned int *log[KVM_NR_PAGE_SIZES], *cur;
int i, j, k, l, ret;
+ if (!kvm_memslots_have_rmaps(kvm))
+ return 0;
+
ret = -ENOMEM;
memset(log, 0, sizeof(log));
for (i = 0; i < KVM_NR_PAGE_SIZES; i++) {