linux-kernel - Re: [PATCH] virtio: uapi: Drop __packed attribute in linux/virtio

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Date: Thu, 25 Jan 2024 23:10:16 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
 Feng Liu <feliu@...dia.com>, Yishai Hadas <yishaih@...dia.com>,
 Alex Williamson <alex.williamson@...hat.com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH] virtio: uapi: Drop __packed attribute in
 linux/virtio_pci.h:

On 25/01/2024 22:48, Michael S. Tsirkin wrote:
> On Wed, Jan 24, 2024 at 05:23:45PM +0000, Suzuki K Poulose wrote:
>> Commit 92792ac752aa ("virtio-pci: Introduce admin command sending function")
>> added "__packed" structures to UAPI header linux/virtio_pci.h. This triggers
>> build failures in the consumer userspace applications without proper "definition"
>> of __packed (e.g., kvmtool build fails).
>>
>> Moreover, the structures are already packed well, and doesn't need explicit
>> packing, similar to the rest of the structures in all virtio_* headers. Remove
>> the __packed attribute.
>>
>> Fixes: commit 92792ac752aa ("virtio-pci: Introduce admin command sending function")
> 
> 
> Proper form is:
> 
> Fixes: 92792ac752aa ("virtio-pci: Introduce admin command sending function")

Apologies, for messing that up.

> 
>> Cc: Feng Liu <feliu@...dia.com>
>> Cc: Michael S. Tsirkin <mst@...hat.com>
>> Cc: Yishai Hadas <yishaih@...dia.com>
>> Cc: Alex Williamson <alex.williamson@...hat.com>
>> Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>> ---
>>   include/uapi/linux/virtio_pci.h | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
>> index ef3810dee7ef..a8208492e822 100644
>> --- a/include/uapi/linux/virtio_pci.h
>> +++ b/include/uapi/linux/virtio_pci.h
>> @@ -240,7 +240,7 @@ struct virtio_pci_cfg_cap {
>>   #define VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_READ		0x5
>>   #define VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO		0x6
>>   
>> -struct __packed virtio_admin_cmd_hdr {
>> +struct virtio_admin_cmd_hdr {
>>   	__le16 opcode;
>>   	/*
>>   	 * 1 - SR-IOV
>> @@ -252,20 +252,20 @@ struct __packed virtio_admin_cmd_hdr {
>>   	__le64 group_member_id;
>>   };
>>   
>> -struct __packed virtio_admin_cmd_status {
>> +struct virtio_admin_cmd_status {
>>   	__le16 status;
>>   	__le16 status_qualifier;
>>   	/* Unused, reserved for future extensions. */
>>   	__u8 reserved2[4];
>>   };
>>   
>> -struct __packed virtio_admin_cmd_legacy_wr_data {
>> +struct virtio_admin_cmd_legacy_wr_data {
>>   	__u8 offset; /* Starting offset of the register(s) to write. */
>>   	__u8 reserved[7];
>>   	__u8 registers[];
>>   };
>>   
>> -struct __packed virtio_admin_cmd_legacy_rd_data {
>> +struct virtio_admin_cmd_legacy_rd_data {
>>   	__u8 offset; /* Starting offset of the register(s) to read. */
>>   };
>>   
>> @@ -275,7 +275,7 @@ struct __packed virtio_admin_cmd_legacy_rd_data {
>>   
>>   #define VIRTIO_ADMIN_CMD_MAX_NOTIFY_INFO 4
>>   
>> -struct __packed virtio_admin_cmd_notify_info_data {
>> +struct virtio_admin_cmd_notify_info_data {
>>   	__u8 flags; /* 0 = end of list, 1 = owner device, 2 = member device */
>>   	__u8 bar; /* BAR of the member or the owner device */
>>   	__u8 padding[6];
> 
> 
> Acked-by: Michael S. Tsirkin <mst@...hat.com>
> 
> I will queue this.

Thanks
Suzuki

> 
>> -- 
>> 2.34.1
>