Re: [PATCH v4 18/20] vfio: Add a new element bypass_ro in VFIOContainerBase

["Cédric Le Goater" <clg@redhat.com>]

On 7/30/25 12:58, Duan, Zhenzhong wrote:
> 
> 
>> -----Original Message-----
>> From: Cédric Le Goater <clg@redhat.com>
>> Subject: Re: [PATCH v4 18/20] vfio: Add a new element bypass_ro in
>> VFIOContainerBase
>>
>> On 7/29/25 11:20, Zhenzhong Duan wrote:
>>> When bypass_ro is true, read only memory section is bypassed from
>>> mapping in the container.
>>>
>>> This is a preparing patch to workaround Intel ERRATA_772415.
>>>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> ---
>>>    include/hw/vfio/vfio-container-base.h |  1 +
>>>    hw/vfio/listener.c                    | 13 +++++++++----
>>>    2 files changed, 10 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/include/hw/vfio/vfio-container-base.h
>> b/include/hw/vfio/vfio-container-base.h
>>> index bded6e993f..31fd784d76 100644
>>> --- a/include/hw/vfio/vfio-container-base.h
>>> +++ b/include/hw/vfio/vfio-container-base.h
>>> @@ -51,6 +51,7 @@ typedef struct VFIOContainerBase {
>>>        QLIST_HEAD(, VFIODevice) device_list;
>>>        GList *iova_ranges;
>>>        NotifierWithReturn cpr_reboot_notifier;
>>> +    bool bypass_ro;
>>>    } VFIOContainerBase;
>>>
>>>    typedef struct VFIOGuestIOMMU {
>>> diff --git a/hw/vfio/listener.c b/hw/vfio/listener.c
>>> index f498e23a93..c64aa4539e 100644
>>> --- a/hw/vfio/listener.c
>>> +++ b/hw/vfio/listener.c
>>> @@ -364,7 +364,8 @@ static bool
>> vfio_known_safe_misalignment(MemoryRegionSection *section)
>>>        return true;
>>>    }
>>>
>>> -static bool vfio_listener_valid_section(MemoryRegionSection *section,
>>> +static bool vfio_listener_valid_section(VFIOContainerBase *bcontainer,
>>> +                                        MemoryRegionSection
>> *section,
>>>                                            const char *name)
>>
>> Instead of adding a 'VFIOContainerBase *' argument, I would add an
>> extra 'bool bypass_ro' argument.
> 
> Done, see https://github.com/yiliu1765/qemu/commit/b0be8bfc9a899334819f3f4f0704e47116944a53

I don't think the extra 'bool bypass_ro' are useful. A part from that,
looks good.


Thanks,

C.


> Opportunistically, I also introduced another patch to bypass dirty tracking for readonly region, see https://github.com/yiliu1765/qemu/commit/a21ce0afd8aec5d5a9e6de46cf46757530cb7d9f