Re: [RFC PATCH] vfio/common: Separate vfio-pci ranges

["Cédric Le Goater" <clg@redhat.com>]

On 9/8/23 10:16, Joao Martins wrote:
> 
> 
> On 08/09/2023 08:14, Cédric Le Goater wrote:
>> From: Joao Martins <joao.m.martins@oracle.com>
>>
>> QEMU computes the DMA logging ranges for two predefined ranges: 32-bit
>> and 64-bit. In the OVMF case, when the dynamic MMIO window is enabled,
>> QEMU includes in the 64-bit range the RAM regions at the lower part
>> and vfio-pci device RAM regions which are at the top of the address
>> space. This range contains a large gap and the size can be bigger than
>> the dirty tracking HW limits of some devices (MLX5 has a 2^42 limit).
>>
>> To avoid such large ranges, introduce a new PCI range covering the
>> vfio-pci device RAM regions, this only if the addresses are above 4GB
>> to avoid breaking potential SeaBIOS guests.
>>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> [ clg: - wrote commit log
>>         - fixed overlapping 32-bit and PCI ranges when using SeaBIOS ]
>> Signed-off-by: Cédric Le Goater <clg@redhat.com>
>> ---
>>   hw/vfio/common.c     | 51 +++++++++++++++++++++++++++++++++++++++-----
>>   hw/vfio/trace-events |  2 +-
>>   2 files changed, 47 insertions(+), 6 deletions(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 237101d03844273f653d98b6d053a1ae9c05a247..a5548e3bebf999e6d9cef08bdaf1fbc3b437e5eb 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -27,6 +27,7 @@
>>   
>>   #include "hw/vfio/vfio-common.h"
>>   #include "hw/vfio/vfio.h"
>> +#include "hw/vfio/pci.h"
>>   #include "exec/address-spaces.h"
>>   #include "exec/memory.h"
>>   #include "exec/ram_addr.h"
>> @@ -1400,6 +1401,8 @@ typedef struct VFIODirtyRanges {
>>       hwaddr max32;
>>       hwaddr min64;
>>       hwaddr max64;
>> +    hwaddr minpci;
>> +    hwaddr maxpci;
> 
> Considering this is about pci64 hole relocation, I wondered post-reading your
> feedback, that maybe we should rename {min,max}pci to {min,max}pci64 (...)

yes.

> 
>>   } VFIODirtyRanges;
>>   
>>   typedef struct VFIODirtyRangesListener {
>> @@ -1408,6 +1411,31 @@ typedef struct VFIODirtyRangesListener {
>>       MemoryListener listener;
>>   } VFIODirtyRangesListener;
>>   
>> +static bool vfio_section_is_vfio_pci(MemoryRegionSection *section,
>> +                                     VFIOContainer *container)
>> +{
>> +    VFIOPCIDevice *pcidev;
>> +    VFIODevice *vbasedev;
>> +    VFIOGroup *group;
>> +    Object *owner;
>> +
>> +    owner = memory_region_owner(section->mr);
>> +
>> +    QLIST_FOREACH(group, &container->group_list, container_next) {
>> +        QLIST_FOREACH(vbasedev, &group->device_list, next) {
>> +            if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
>> +                continue;
>> +            }
>> +            pcidev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>> +            if (OBJECT(pcidev) == owner) {
>> +                return true;
>> +            }
>> +        }
>> +    }
>> +
>> +    return false;
>> +}
>> +
>>   static void vfio_dirty_tracking_update(MemoryListener *listener,
>>                                          MemoryRegionSection *section)
>>   {
>> @@ -1434,9 +1462,14 @@ static void vfio_dirty_tracking_update(MemoryListener *listener,
>>        * would be an IOVATree but that has a much bigger runtime overhead and
>>        * unnecessary complexity.
>>        */
>> -    min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
>> -    max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
>> -
>> +    if (vfio_section_is_vfio_pci(section, dirty->container) &&
>> +        iova >= UINT32_MAX) {
>> +        min = &range->minpci;
>> +        max = &range->maxpci;
> 
> (...) specially considering this check of making sure we skip the pci-hole32 (as
> that one is fixed)

yep. That check above might deserve a comment also.

Could you resend please ?

Thanks,

C.


> 
>> +    } else {
>> +        min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
>> +        max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
>> +    }
>>       if (*min > iova) {
>>           *min = iova;
>>       }
>> @@ -1461,6 +1494,7 @@ static void vfio_dirty_tracking_init(VFIOContainer *container,
>>       memset(&dirty, 0, sizeof(dirty));
>>       dirty.ranges.min32 = UINT32_MAX;
>>       dirty.ranges.min64 = UINT64_MAX;
>> +    dirty.ranges.minpci = UINT64_MAX;
>>       dirty.listener = vfio_dirty_tracking_listener;
>>       dirty.container = container;
>>   
>> @@ -1531,7 +1565,8 @@ vfio_device_feature_dma_logging_start_create(VFIOContainer *container,
>>        * DMA logging uAPI guarantees to support at least a number of ranges that
>>        * fits into a single host kernel base page.
>>        */
>> -    control->num_ranges = !!tracking->max32 + !!tracking->max64;
>> +    control->num_ranges = !!tracking->max32 + !!tracking->max64 +
>> +        !!tracking->maxpci;
>>       ranges = g_try_new0(struct vfio_device_feature_dma_logging_range,
>>                           control->num_ranges);
>>       if (!ranges) {
>> @@ -1550,11 +1585,17 @@ vfio_device_feature_dma_logging_start_create(VFIOContainer *container,
>>       if (tracking->max64) {
>>           ranges->iova = tracking->min64;
>>           ranges->length = (tracking->max64 - tracking->min64) + 1;
>> +        ranges++;
>> +    }
>> +    if (tracking->maxpci) {
>> +        ranges->iova = tracking->minpci;
>> +        ranges->length = (tracking->maxpci - tracking->minpci) + 1;
>>       }
>>   
>>       trace_vfio_device_dirty_tracking_start(control->num_ranges,
>>                                              tracking->min32, tracking->max32,
>> -                                           tracking->min64, tracking->max64);
>> +                                           tracking->min64, tracking->max64,
>> +                                           tracking->minpci, tracking->maxpci);
>>   
>>       return feature;
>>   }
>> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
>> index ce61b10827b6a1203a5fe1a87a76d96f25c11345..ab52c6bb7f0c11e51fefef231c108d0c9381547e 100644
>> --- a/hw/vfio/trace-events
>> +++ b/hw/vfio/trace-events
>> @@ -104,7 +104,7 @@ vfio_known_safe_misalignment(const char *name, uint64_t iova, uint64_t offset_wi
>>   vfio_listener_region_add_no_dma_map(const char *name, uint64_t iova, uint64_t size, uint64_t page_size) "Region \"%s\" 0x%"PRIx64" size=0x%"PRIx64" is not aligned to 0x%"PRIx64" and cannot be mapped for DMA"
>>   vfio_listener_region_del(uint64_t start, uint64_t end) "region_del 0x%"PRIx64" - 0x%"PRIx64
>>   vfio_device_dirty_tracking_update(uint64_t start, uint64_t end, uint64_t min, uint64_t max) "section 0x%"PRIx64" - 0x%"PRIx64" -> update [0x%"PRIx64" - 0x%"PRIx64"]"
>> -vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t max32, uint64_t min64, uint64_t max64) "nr_ranges %d 32:[0x%"PRIx64" - 0x%"PRIx64"], 64:[0x%"PRIx64" - 0x%"PRIx64"]"
>> +vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t max32, uint64_t min64, uint64_t max64, uint64_t minpci, uint64_t maxpci) "nr_ranges %d 32:[0x%"PRIx64" - 0x%"PRIx64"], 64:[0x%"PRIx64" - 0x%"PRIx64"], pci:[0x%"PRIx64" - 0x%"PRIx64"]"
>>   vfio_disconnect_container(int fd) "close container->fd=%d"
>>   vfio_put_group(int fd) "close group->fd=%d"
>>   vfio_get_device(const char * name, unsigned int flags, unsigned int num_regions, unsigned int num_irqs) "Device %s flags: %u, regions: %u, irqs: %u"
>