* [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
@ 2025-07-21 6:52 Xiaoyao Li
2025-07-21 7:50 ` Stefano Garzarella
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Xiaoyao Li @ 2025-07-21 6:52 UTC (permalink / raw)
To: David Hildenbrand, Igor Mammedov, Paolo Bonzini
Cc: qemu-devel, Xiaoyao Li, Stefano Garzarella
shm can surely serve as the shared memory for coco-VMs. But currently it
doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
require private mmeory.
Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
allow shm memory backend serve as shared memory for coco-VMs.
cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
backends/hostmem-shm.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
index f66211a2ec92..806e2670e039 100644
--- a/backends/hostmem-shm.c
+++ b/backends/hostmem-shm.c
@@ -54,6 +54,7 @@ have_fd:
/* Let's do the same as memory-backend-ram,share=on would do. */
ram_flags = RAM_SHARED;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+ ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
backend_name, backend->size,
--
2.43.0
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
2025-07-21 6:52 [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs Xiaoyao Li
@ 2025-07-21 7:50 ` Stefano Garzarella
2025-07-21 8:00 ` David Hildenbrand
2025-08-14 9:45 ` Xiaoyao Li
2 siblings, 0 replies; 7+ messages in thread
From: Stefano Garzarella @ 2025-07-21 7:50 UTC (permalink / raw)
To: Xiaoyao Li; +Cc: David Hildenbrand, Igor Mammedov, Paolo Bonzini, qemu-devel
On Mon, Jul 21, 2025 at 02:52:20PM +0800, Xiaoyao Li wrote:
>shm can surely serve as the shared memory for coco-VMs. But currently it
>doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
>flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
>require private mmeory.
>
>Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
>allow shm memory backend serve as shared memory for coco-VMs.
>
>cc: Stefano Garzarella <sgarzare@redhat.com>
>Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>---
> backends/hostmem-shm.c | 1 +
> 1 file changed, 1 insertion(+)
LGTM!
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Thanks,
Stefano
>
>diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
>index f66211a2ec92..806e2670e039 100644
>--- a/backends/hostmem-shm.c
>+++ b/backends/hostmem-shm.c
>@@ -54,6 +54,7 @@ have_fd:
> /* Let's do the same as memory-backend-ram,share=on would do. */
> ram_flags = RAM_SHARED;
> ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
>+ ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
>
> return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
> backend_name, backend->size,
>--
>2.43.0
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
2025-07-21 6:52 [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs Xiaoyao Li
2025-07-21 7:50 ` Stefano Garzarella
@ 2025-07-21 8:00 ` David Hildenbrand
2025-08-14 9:45 ` Xiaoyao Li
2 siblings, 0 replies; 7+ messages in thread
From: David Hildenbrand @ 2025-07-21 8:00 UTC (permalink / raw)
To: Xiaoyao Li, Igor Mammedov, Paolo Bonzini; +Cc: qemu-devel, Stefano Garzarella
On 21.07.25 08:52, Xiaoyao Li wrote:
> shm can surely serve as the shared memory for coco-VMs. But currently it
> doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
> flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
> require private mmeory.
>
> Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
> allow shm memory backend serve as shared memory for coco-VMs.
>
> cc: Stefano Garzarella <sgarzare@redhat.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
--
Cheers,
David / dhildenb
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
2025-07-21 6:52 [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs Xiaoyao Li
2025-07-21 7:50 ` Stefano Garzarella
2025-07-21 8:00 ` David Hildenbrand
@ 2025-08-14 9:45 ` Xiaoyao Li
2025-09-12 5:45 ` Xiaoyao Li
2 siblings, 1 reply; 7+ messages in thread
From: Xiaoyao Li @ 2025-08-14 9:45 UTC (permalink / raw)
To: David Hildenbrand, Igor Mammedov, Paolo Bonzini
Cc: qemu-devel, Stefano Garzarella
On 7/21/2025 2:52 PM, Xiaoyao Li wrote:
> shm can surely serve as the shared memory for coco-VMs. But currently it
> doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
> flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
> require private mmeory.
>
> Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
> allow shm memory backend serve as shared memory for coco-VMs.
ping...
Paolo, will you merge it for QEMU 10.1? I think it's worth it.
> cc: Stefano Garzarella <sgarzare@redhat.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
> backends/hostmem-shm.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
> index f66211a2ec92..806e2670e039 100644
> --- a/backends/hostmem-shm.c
> +++ b/backends/hostmem-shm.c
> @@ -54,6 +54,7 @@ have_fd:
> /* Let's do the same as memory-backend-ram,share=on would do. */
> ram_flags = RAM_SHARED;
> ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
> + ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
>
> return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
> backend_name, backend->size,
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
2025-08-14 9:45 ` Xiaoyao Li
@ 2025-09-12 5:45 ` Xiaoyao Li
2025-10-24 0:51 ` Xiaoyao Li
0 siblings, 1 reply; 7+ messages in thread
From: Xiaoyao Li @ 2025-09-12 5:45 UTC (permalink / raw)
To: David Hildenbrand, Igor Mammedov, Paolo Bonzini
Cc: qemu-devel, Stefano Garzarella
On 8/14/2025 5:45 PM, Xiaoyao Li wrote:
> On 7/21/2025 2:52 PM, Xiaoyao Li wrote:
>> shm can surely serve as the shared memory for coco-VMs. But currently it
>> doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
>> flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
>> require private mmeory.
>>
>> Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
>> allow shm memory backend serve as shared memory for coco-VMs.
>
> ping...
>
> Paolo, will you merge it for QEMU 10.1? I think it's worth it.
ping again.
>> cc: Stefano Garzarella <sgarzare@redhat.com>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>> ---
>> backends/hostmem-shm.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
>> index f66211a2ec92..806e2670e039 100644
>> --- a/backends/hostmem-shm.c
>> +++ b/backends/hostmem-shm.c
>> @@ -54,6 +54,7 @@ have_fd:
>> /* Let's do the same as memory-backend-ram,share=on would do. */
>> ram_flags = RAM_SHARED;
>> ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
>> + ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
>> return memory_region_init_ram_from_fd(&backend->mr,
>> OBJECT(backend),
>> backend_name, backend-
>> >size,
>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
2025-09-12 5:45 ` Xiaoyao Li
@ 2025-10-24 0:51 ` Xiaoyao Li
2025-10-24 15:52 ` Peter Xu
0 siblings, 1 reply; 7+ messages in thread
From: Xiaoyao Li @ 2025-10-24 0:51 UTC (permalink / raw)
To: David Hildenbrand, Igor Mammedov, Paolo Bonzini, Peter Xu
Cc: qemu-devel, Stefano Garzarella
On 9/12/2025 1:45 PM, Xiaoyao Li wrote:
> On 8/14/2025 5:45 PM, Xiaoyao Li wrote:
>> On 7/21/2025 2:52 PM, Xiaoyao Li wrote:
>>> shm can surely serve as the shared memory for coco-VMs. But currently it
>>> doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
>>> flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
>>> require private mmeory.
>>>
>>> Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
>>> allow shm memory backend serve as shared memory for coco-VMs.
>>
>> ping...
>>
>> Paolo, will you merge it for QEMU 10.1? I think it's worth it.
>
> ping again.
ping++,
+ Peter,
Maybe you can queue it in case it gets missed from Paolo again?
>>> cc: Stefano Garzarella <sgarzare@redhat.com>
>>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>>> ---
>>> backends/hostmem-shm.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/backends/hostmem-shm.c b/backends/hostmem-shm.c
>>> index f66211a2ec92..806e2670e039 100644
>>> --- a/backends/hostmem-shm.c
>>> +++ b/backends/hostmem-shm.c
>>> @@ -54,6 +54,7 @@ have_fd:
>>> /* Let's do the same as memory-backend-ram,share=on would do. */
>>> ram_flags = RAM_SHARED;
>>> ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
>>> + ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
>>> return memory_region_init_ram_from_fd(&backend->mr,
>>> OBJECT(backend),
>>> backend_name,
>>> backend- >size,
>>
>>
>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs
2025-10-24 0:51 ` Xiaoyao Li
@ 2025-10-24 15:52 ` Peter Xu
0 siblings, 0 replies; 7+ messages in thread
From: Peter Xu @ 2025-10-24 15:52 UTC (permalink / raw)
To: Xiaoyao Li
Cc: David Hildenbrand, Igor Mammedov, Paolo Bonzini, qemu-devel,
Stefano Garzarella
On Fri, Oct 24, 2025 at 08:51:35AM +0800, Xiaoyao Li wrote:
> On 9/12/2025 1:45 PM, Xiaoyao Li wrote:
> > On 8/14/2025 5:45 PM, Xiaoyao Li wrote:
> > > On 7/21/2025 2:52 PM, Xiaoyao Li wrote:
> > > > shm can surely serve as the shared memory for coco-VMs. But currently it
> > > > doesn't check the backend->guest_memfd to pass down the RAM_GUEST_MEMFD
> > > > flag. It leads to failure when creating coco-VMs (e.g., TDX guest) which
> > > > require private mmeory.
> > > >
> > > > Set and pass down RAM_GUEST_MEMFD when backend->guest_memfd is true, to
> > > > allow shm memory backend serve as shared memory for coco-VMs.
> > >
> > > ping...
> > >
> > > Paolo, will you merge it for QEMU 10.1? I think it's worth it.
> >
> > ping again.
>
> ping++,
>
> + Peter,
>
> Maybe you can queue it in case it gets missed from Paolo again?
Yep, queued now and I copied stable, let me know otherwise. Thanks.
--
Peter Xu
^ permalink raw reply [flat|nested] 7+ messages in thread
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2025-07-21 6:52 [PATCH] hostmem/shm: Allow shm memory backend serve as shared memory for coco-VMs Xiaoyao Li
2025-07-21 7:50 ` Stefano Garzarella
2025-07-21 8:00 ` David Hildenbrand
2025-08-14 9:45 ` Xiaoyao Li
2025-09-12 5:45 ` Xiaoyao Li
2025-10-24 0:51 ` Xiaoyao Li
2025-10-24 15:52 ` Peter Xu
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