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Re: [PATCH QEMU v23 16/18] vfio: Add ioctl to get dirty pages bitmap dur
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH QEMU v23 16/18] vfio: Add ioctl to get dirty pages bitmap during dma unmap. |
Date: |
Thu, 21 May 2020 20:05:41 +0100 |
User-agent: |
Mutt/1.13.4 (2020-02-15) |
* Kirti Wankhede (address@hidden) wrote:
> With vIOMMU, IO virtual address range can get unmapped while in pre-copy
> phase of migration. In that case, unmap ioctl should return pages pinned
> in that range and QEMU should find its correcponding guest physical
> addresses and report those dirty.
>
> Suggested-by: Alex Williamson <address@hidden>
> Signed-off-by: Kirti Wankhede <address@hidden>
> Reviewed-by: Neo Jia <address@hidden>
> ---
> hw/vfio/common.c | 84
> +++++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 80 insertions(+), 4 deletions(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 3f7049fbd1b0..2dd9e8b24788 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -311,11 +311,82 @@ static bool vfio_devices_are_stopped_and_saving(void)
> return true;
> }
>
> +static bool vfio_devices_are_running_and_saving(void)
> +{
> + VFIOGroup *group;
> + VFIODevice *vbasedev;
> +
> + QLIST_FOREACH(group, &vfio_group_list, next) {
> + QLIST_FOREACH(vbasedev, &group->device_list, next) {
> + if ((vbasedev->device_state & VFIO_DEVICE_STATE_SAVING) &&
> + (vbasedev->device_state & VFIO_DEVICE_STATE_RUNNING)) {
> + continue;
> + } else {
> + return false;
> + }
> + }
> + }
> + return true;
> +}
> +
> +static int vfio_dma_unmap_bitmap(VFIOContainer *container,
> + hwaddr iova, ram_addr_t size,
> + IOMMUTLBEntry *iotlb)
> +{
> + struct vfio_iommu_type1_dma_unmap *unmap;
> + struct vfio_bitmap *bitmap;
> + uint64_t pages = TARGET_PAGE_ALIGN(size) >> TARGET_PAGE_BITS;
> + int ret;
> +
> + unmap = g_malloc0(sizeof(*unmap) + sizeof(*bitmap));
> + if (!unmap) {
> + return -ENOMEM;
> + }
Again that's a fixed size thing so you don't really need to malloc it;
g_malloc0 won't return NULL; it'll just assert (which it shouldn't
do anyway because those structures are small). Personally I'd just put
it on the stack.
> + unmap->argsz = sizeof(*unmap) + sizeof(*bitmap);
> + unmap->iova = iova;
> + unmap->size = size;
> + unmap->flags |= VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP;
> + bitmap = (struct vfio_bitmap *)&unmap->data;
> +
> + /*
> + * cpu_physical_memory_set_dirty_lebitmap() expects pages in bitmap of
> + * TARGET_PAGE_SIZE to mark those dirty. Hence set bitmap_pgsize to
> + * TARGET_PAGE_SIZE.
> + */
> +
> + bitmap->pgsize = TARGET_PAGE_SIZE;
> + bitmap->size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) /
> + BITS_PER_BYTE;
> +
> + if (bitmap->size > container->max_dirty_bitmap_size) {
> + error_report("UNMAP: Size of bitmap too big 0x%llx", bitmap->size);
> + ret = -E2BIG;
> + goto unmap_exit;
> + }
> +
> + bitmap->data = g_malloc0(bitmap->size);
That one should be a g_try_malloc0 and check it's non-null.
> +
> + ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap);
> + if (!ret) {
> + cpu_physical_memory_set_dirty_lebitmap((uint64_t *)bitmap->data,
> + iotlb->translated_addr, pages);
> + } else {
> + error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %d", -errno);
You're allowed touse %m in hw/vfio for printing the error nicely.
> + }
> +
> + g_free(bitmap->data);
> +unmap_exit:
> + g_free(unmap);
> + return ret;
> +}
> +
> /*
> * DMA - Mapping and unmapping for the "type1" IOMMU interface used on x86
> */
> static int vfio_dma_unmap(VFIOContainer *container,
> - hwaddr iova, ram_addr_t size)
> + hwaddr iova, ram_addr_t size,
> + IOMMUTLBEntry *iotlb)
> {
> struct vfio_iommu_type1_dma_unmap unmap = {
> .argsz = sizeof(unmap),
> @@ -324,6 +395,11 @@ static int vfio_dma_unmap(VFIOContainer *container,
> .size = size,
> };
>
> + if (iotlb && container->dirty_pages_supported &&
> + vfio_devices_are_running_and_saving()) {
> + return vfio_dma_unmap_bitmap(container, iova, size, iotlb);
> + }
> +
> while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
> /*
> * The type1 backend has an off-by-one bug in the kernel
> (71a7d3d78e3c
> @@ -371,7 +447,7 @@ static int vfio_dma_map(VFIOContainer *container, hwaddr
> iova,
> * the VGA ROM space.
> */
> if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0 ||
> - (errno == EBUSY && vfio_dma_unmap(container, iova, size) == 0 &&
> + (errno == EBUSY && vfio_dma_unmap(container, iova, size, NULL) == 0
> &&
> ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0)) {
> return 0;
> }
> @@ -519,7 +595,7 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n,
> IOMMUTLBEntry *iotlb)
> iotlb->addr_mask + 1, vaddr, ret);
> }
> } else {
> - ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1);
> + ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1, iotlb);
> if (ret) {
> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
> "0x%"HWADDR_PRIx") = %d (%m)",
> @@ -822,7 +898,7 @@ static void vfio_listener_region_del(MemoryListener
> *listener,
> }
>
> if (try_unmap) {
> - ret = vfio_dma_unmap(container, iova, int128_get64(llsize));
> + ret = vfio_dma_unmap(container, iova, int128_get64(llsize), NULL);
> if (ret) {
> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
> "0x%"HWADDR_PRIx") = %d (%m)",
> --
> 2.7.0
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [PATCH QEMU v23 11/18] iommu: add callback to get address limit IOMMU supports, (continued)
- [PATCH QEMU v23 11/18] iommu: add callback to get address limit IOMMU supports, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 12/18] memory: Set DIRTY_MEMORY_MIGRATION when IOMMU is enabled, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 13/18] vfio: Get migration capability flags for container, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 14/18] vfio: Add function to start and stop dirty pages tracking, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 15/18] vfio: Add vfio_listener_log_sync to mark dirty pages, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 16/18] vfio: Add ioctl to get dirty pages bitmap during dma unmap., Kirti Wankhede, 2020/05/20
- Re: [PATCH QEMU v23 16/18] vfio: Add ioctl to get dirty pages bitmap during dma unmap.,
Dr. David Alan Gilbert <=
- [PATCH QEMU v23 17/18] vfio: Make vfio-pci device migration capable, Kirti Wankhede, 2020/05/20
- [PATCH QEMU v23 18/18] qapi: Add VFIO devices migration stats in Migration stats, Kirti Wankhede, 2020/05/20