* [PATCH v2] KVM: x86: Check for rmaps allocation
@ 2022-01-05 4:03 Nikunj A Dadhania
2022-01-05 9:07 ` Peter Xu
2022-01-07 17:08 ` Paolo Bonzini
0 siblings, 2 replies; 6+ messages in thread
From: Nikunj A Dadhania @ 2022-01-05 4:03 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Peter Xu, kvm,
linux-kernel, nikunj, vasant.hegde, brijesh.singh
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>
---
v1: https://lore.kernel.org/kvm/20220104092814.11553-1-nikunj@amd.com/T/#u
Check the rmaps inside kvm_mmu_rmaps_stat_show() as the rmaps can be
allocated dynamically (Peter Xu)
arch/x86/kvm/debugfs.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index 543a8c04025c..9240b3b7f8dd 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++) {
--
2.32.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v2] KVM: x86: Check for rmaps allocation
2022-01-05 4:03 [PATCH v2] KVM: x86: Check for rmaps allocation Nikunj A Dadhania
@ 2022-01-05 9:07 ` Peter Xu
2022-01-07 17:01 ` Sean Christopherson
2022-01-07 17:08 ` Paolo Bonzini
1 sibling, 1 reply; 6+ messages in thread
From: Peter Xu @ 2022-01-05 9:07 UTC (permalink / raw)
To: Nikunj A Dadhania
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, kvm,
linux-kernel, vasant.hegde, brijesh.singh
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>
> ---
>
> v1: https://lore.kernel.org/kvm/20220104092814.11553-1-nikunj@amd.com/T/#u
>
> Check the rmaps inside kvm_mmu_rmaps_stat_show() as the rmaps can be
> allocated dynamically (Peter Xu)
>
> arch/x86/kvm/debugfs.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
> index 543a8c04025c..9240b3b7f8dd 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++) {
> --
> 2.32.0
>
Reviewed-by: Peter Xu <peterx@redhat.com>
Thanks,
--
Peter Xu
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] KVM: x86: Check for rmaps allocation
2022-01-05 9:07 ` Peter Xu
@ 2022-01-07 17:01 ` Sean Christopherson
2022-01-07 17:03 ` Paolo Bonzini
2022-01-07 17:04 ` Paolo Bonzini
0 siblings, 2 replies; 6+ messages in thread
From: Sean Christopherson @ 2022-01-07 17:01 UTC (permalink / raw)
To: Peter Xu
Cc: Nikunj A Dadhania, Paolo Bonzini, Vitaly Kuznetsov, kvm,
linux-kernel, vasant.hegde, brijesh.singh
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>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] KVM: x86: Check for rmaps allocation
2022-01-07 17:01 ` Sean Christopherson
@ 2022-01-07 17:03 ` Paolo Bonzini
2022-01-07 17:04 ` Paolo Bonzini
1 sibling, 0 replies; 6+ messages in thread
From: Paolo Bonzini @ 2022-01-07 17:03 UTC (permalink / raw)
To: Sean Christopherson, Peter Xu
Cc: Nikunj A Dadhania, Vitaly Kuznetsov, kvm, linux-kernel,
vasant.hegde, brijesh.singh
On 1/7/22 18:01, Sean Christopherson wrote:
> 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>
>
Queued, thanks.
paolo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] KVM: x86: Check for rmaps allocation
2022-01-07 17:01 ` Sean Christopherson
2022-01-07 17:03 ` Paolo Bonzini
@ 2022-01-07 17:04 ` Paolo Bonzini
1 sibling, 0 replies; 6+ messages in thread
From: Paolo Bonzini @ 2022-01-07 17:04 UTC (permalink / raw)
To: Sean Christopherson, Peter Xu
Cc: Nikunj A Dadhania, Vitaly Kuznetsov, kvm, linux-kernel,
vasant.hegde, brijesh.singh
On 1/7/22 18:01, Sean Christopherson wrote:
> 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>
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] KVM: x86: Check for rmaps allocation
2022-01-05 4:03 [PATCH v2] KVM: x86: Check for rmaps allocation Nikunj A Dadhania
2022-01-05 9:07 ` Peter Xu
@ 2022-01-07 17:08 ` Paolo Bonzini
1 sibling, 0 replies; 6+ messages in thread
From: Paolo Bonzini @ 2022-01-07 17:08 UTC (permalink / raw)
To: Nikunj A Dadhania
Cc: Sean Christopherson, Vitaly Kuznetsov, Peter Xu, kvm,
linux-kernel, vasant.hegde, brijesh.singh
On 1/5/22 05:03, 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>
> ---
>
> v1: https://lore.kernel.org/kvm/20220104092814.11553-1-nikunj@amd.com/T/#u
>
> Check the rmaps inside kvm_mmu_rmaps_stat_show() as the rmaps can be
> allocated dynamically (Peter Xu)
>
> arch/x86/kvm/debugfs.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
> index 543a8c04025c..9240b3b7f8dd 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++) {
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-01-07 17:08 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2022-01-05 4:03 [PATCH v2] KVM: x86: Check for rmaps allocation Nikunj A Dadhania
2022-01-05 9:07 ` Peter Xu
2022-01-07 17:01 ` Sean Christopherson
2022-01-07 17:03 ` Paolo Bonzini
2022-01-07 17:04 ` Paolo Bonzini
2022-01-07 17:08 ` Paolo Bonzini
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