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SubjectRe: [PATCH v2] KVM: x86: Check for rmaps allocation
On Wed, Jan 05, 2022, Peter Xu wrote:
> On Wed, Jan 05, 2022 at 09:33:37AM +0530, Nikunj A Dadhania wrote:
> > 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: Sean Christopherson <seanjc@google.com>

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