On 26/01/18 00:56, Auger Eric wrote:
> Hi Alexey,
>
> On 25/01/18 05:22, Alexey Kardashevskiy wrote:
>> This makes use of a new VFIO_REGION_INFO_CAP_MSIX_MAPPABLE capability
>> which tells that a region with MSIX data can be mapped entirely, i.e.
>> the VFIO PCI driver won't prevent MSIX vectors area from being mapped.
>>
>> With this change, all BARs are mapped in a single chunk and MSIX vectors
>> are emulated on top unless the machine requests not to by defining and
>> enabling a new "vfio-no-msix-emulation" property. At the moment only
>> sPAPR machine does so - it prohibits MSIX emulation and does not allow
>> enabling it as it does not define the "set" callback for the new property;
>> the new property also does not appear in "-machine pseries,help".
>>
>> If MSIX vectors section is not aligned to the page size, the KVM memory
>> listener does not register it with the KVM as a memory slot and MSIX is
>> emulated by QEMU as before. This may create MMIO RAM memory sections with
>> an address or/and a size not aligned which will make vfio_dma_map() fail;
>> to address this, this treats such failures as non-fatal and does not print
>> an error. This adds a return value from vfio_dma_map() to the tracepoint
>> and moves the latter further down to let the user have a clue why P2P
>> might not work.
>>
>> This requires the kernel change - "vfio-pci: Allow mapping MSIX BAR" -
>> for the new capability: https://www.spinics.net/lists/kvm/msg160282.html
>>
>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
>> ---
>> Changes:
>> v4:
>> * silenced dma map errors if unaligned mapping is attempted - they are going
>> to fail anyway
>>
>> v3:
>> * vfio_listener_region_add() won't make qemu exit if failed on MMIO MR
>> ---
>> include/hw/vfio/vfio-common.h | 1 +
>> linux-headers/linux/vfio.h | 5 +++++
>> hw/ppc/spapr.c | 7 +++++++
>> hw/vfio/common.c | 27 +++++++++++++++++++++++++--
>> hw/vfio/pci.c | 10 ++++++++++
>> hw/vfio/trace-events | 2 +-
>> 6 files changed, 49 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
>> index f3a2ac9..927d600 100644
>> --- a/include/hw/vfio/vfio-common.h
>> +++ b/include/hw/vfio/vfio-common.h
>> @@ -171,6 +171,7 @@ int vfio_get_region_info(VFIODevice *vbasedev, int index,
>> struct vfio_region_info **info);
>> int vfio_get_dev_region_info(VFIODevice *vbasedev, uint32_t type,
>> uint32_t subtype, struct vfio_region_info
>> **info);
>> +bool vfio_is_cap_present(VFIODevice *vbasedev, uint16_t cap_type, int
>> region);
>> #endif
>> extern const MemoryListener vfio_prereg_listener;
>>
>> diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
>> index 4312e96..b45182e 100644
>> --- a/linux-headers/linux/vfio.h
>> +++ b/linux-headers/linux/vfio.h
>> @@ -301,6 +301,11 @@ struct vfio_region_info_cap_type {
>> #define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG (2)
>> #define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG (3)
>>
>> +/*
>> + * The MSIX mappable capability informs that MSIX data of a BAR can be
>> mmapped.
>> + */
>> +#define VFIO_REGION_INFO_CAP_MSIX_MAPPABLE 3
>> +
>> /**
>> * VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,
>> * struct vfio_irq_info)
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index d1acfe8..5ff43ce 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -2789,6 +2789,11 @@ static void spapr_set_modern_hotplug_events(Object
>> *obj, bool value,
>> spapr->use_hotplug_event_source = value;
>> }
>>
>> +static bool spapr_get_msix_emulation(Object *obj, Error **errp)
>> +{
>> + return true;
>> +}
>> +
>> static char *spapr_get_resize_hpt(Object *obj, Error **errp)
>> {
>> sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
>> @@ -2870,6 +2875,8 @@ static void spapr_instance_init(Object *obj)
>> object_property_set_description(obj, "vsmt",
>> "Virtual SMT: KVM behaves as if this
>> were"
>> " the host's SMT mode", &error_abort);
>> + object_property_add_bool(obj, "vfio-no-msix-emulation",
>> + spapr_get_msix_emulation, NULL, NULL);
>> }
>>
>> static void spapr_machine_finalizefn(Object *obj)
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 3d652c8..04a8280 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -513,13 +513,21 @@ static void vfio_listener_region_add(MemoryListener
>> *listener,
>> section->offset_within_region +
>> (iova - section->offset_within_address_space);
>>
>> - trace_vfio_listener_region_add_ram(iova, end, vaddr);
>> -
>> llsize = int128_sub(llend, int128_make64(iova));
>>
>> ret = vfio_dma_map(container, iova, int128_get64(llsize),
>> vaddr, section->readonly);
>> + trace_vfio_listener_region_add_ram(iova, end, vaddr, ret);
>> +
>> if (ret) {
>> + hwaddr pgmask = (1ULL << ctz64(hostwin->iova_pgsizes)) - 1;
>> +
>> + if (memory_region_is_ram_device(section->mr) &&
>> + ((section->offset_within_region & pgmask) ||
>> + (int128_getlo(section->size) & pgmask))) {
>> + return;
>> + }
>> +
> Why not avoiding to call vfio_dma_map in this case and print a helpful
> message for the end-user?
Avoiding is a good point, but I am not sure about the message though. I am
leaning towards disabling these regions from being dma mapped by default
and have a machine option for it, for example. We do not need this in most
cases but if we do, we actually want to see every failed dma map request. I
am just not sure about that property interface.
> qemu-system-aarch64: VFIO_UNMAP_DMA: -22
Ah, missed this.
> qemu-system-aarch64: vfio_dma_unmap(0xc0dab90, 0x8000000000, 0x2000) =
> -22 (Invalid argument)
>
> is not self-explanatory I think.
What is missing?
>
> Thanks
>
> Eric
>> error_report("vfio_dma_map(%p, 0x%"HWADDR_PRIx", "
>> "0x%"HWADDR_PRIx", %p) = %d (%m)",
>> container, iova, int128_get64(llsize), vaddr, ret);
>> @@ -1386,6 +1394,21 @@ int vfio_get_dev_region_info(VFIODevice *vbasedev,
>> uint32_t type,
>> return -ENODEV;
>> }
>>
>> +bool vfio_is_cap_present(VFIODevice *vbasedev, uint16_t cap_type, int
>> region)
>> +{
>> + struct vfio_region_info *info = NULL;
>> + bool ret = false;
>> +
>> + if (!vfio_get_region_info(vbasedev, region, &info)) {
>> + if (vfio_get_region_info_cap(info, cap_type)) {
>> + ret = true;
>> + }
>> + g_free(info);
>> + }
>> +
>> + return ret;
>> +}
>> +
>> /*
>> * Interfaces for IBM EEH (Enhanced Error Handling)
>> */
>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>> index 359a8f1..a96ece6 100644
>> --- a/hw/vfio/pci.c
>> +++ b/hw/vfio/pci.c
>> @@ -1289,6 +1289,11 @@ static void vfio_pci_fixup_msix_region(VFIOPCIDevice
>> *vdev)
>> off_t start, end;
>> VFIORegion *region = &vdev->bars[vdev->msix->table_bar].region;
>>
>> + if (vfio_is_cap_present(&vdev->vbasedev,
>> VFIO_REGION_INFO_CAP_MSIX_MAPPABLE,
>> + vdev->msix->table_bar)) {
>> + return;
>> + }
>> +
>> /*
>> * We expect to find a single mmap covering the whole BAR, anything else
>> * means it's either unsupported or already setup.
>> @@ -1569,6 +1574,11 @@ static int vfio_msix_setup(VFIOPCIDevice *vdev, int
>> pos, Error **errp)
>> */
>> memory_region_set_enabled(&vdev->pdev.msix_pba_mmio, false);
>>
>> + if (object_property_get_bool(OBJECT(qdev_get_machine()),
>> + "vfio-no-msix-emulation", NULL)) {
>> + memory_region_set_enabled(&vdev->pdev.msix_table_mmio, false);
>> + }
>> +
>> return 0;
>> }
>>
>> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
>> index 437ccdd..d747c11 100644
>> --- a/hw/vfio/trace-events
>> +++ b/hw/vfio/trace-events
>> @@ -89,7 +89,7 @@ vfio_region_read(char *name, int index, uint64_t addr,
>> unsigned size, uint64_t d
>> vfio_iommu_map_notify(const char *op, uint64_t iova_start, uint64_t
>> iova_end) "iommu %s @ 0x%"PRIx64" - 0x%"PRIx64
>> vfio_listener_region_add_skip(uint64_t start, uint64_t end) "SKIPPING
>> region_add 0x%"PRIx64" - 0x%"PRIx64
>> vfio_listener_region_add_iommu(uint64_t start, uint64_t end) "region_add
>> [iommu] 0x%"PRIx64" - 0x%"PRIx64
>> -vfio_listener_region_add_ram(uint64_t iova_start, uint64_t iova_end, void
>> *vaddr) "region_add [ram] 0x%"PRIx64" - 0x%"PRIx64" [%p]"
>> +vfio_listener_region_add_ram(uint64_t iova_start, uint64_t iova_end, void
>> *vaddr, int ret) "region_add [ram] 0x%"PRIx64" - 0x%"PRIx64" [%p] ret=%d"
>> vfio_listener_region_del_skip(uint64_t start, uint64_t end) "SKIPPING
>> region_del 0x%"PRIx64" - 0x%"PRIx64
>> vfio_listener_region_del(uint64_t start, uint64_t end) "region_del
>> 0x%"PRIx64" - 0x%"PRIx64
>> vfio_disconnect_container(int fd) "close container->fd=%d"
>>
--
Alexey
