[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RFC 1/3] util/vfio-helpers: Collect IOVA reserved regions
From: |
Fam Zheng |
Subject: |
Re: [RFC 1/3] util/vfio-helpers: Collect IOVA reserved regions |
Date: |
Fri, 25 Sep 2020 15:43:07 +0100 |
On 2020-09-25 15:48, Eric Auger wrote:
> The IOVA allocator currently ignores host reserved regions.
> As a result some chosen IOVAs may collide with some of them,
> resulting in VFIO MAP_DMA errors later on. This happens on ARM
> where the MSI reserved window quickly is encountered:
> [0x8000000, 0x8100000]. since 5.4 kernel, VFIO returns the usable
> IOVA regions. So let's enumerate them in the prospect to avoid
> them, later on.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> util/vfio-helpers.c | 75 +++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 73 insertions(+), 2 deletions(-)
>
> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
> index 583bdfb36f..8e91beba95 100644
> --- a/util/vfio-helpers.c
> +++ b/util/vfio-helpers.c
> @@ -40,6 +40,11 @@ typedef struct {
> uint64_t iova;
> } IOVAMapping;
>
> +struct IOVARange {
> + uint64_t start;
> + uint64_t end;
> +};
> +
> struct QEMUVFIOState {
> QemuMutex lock;
>
> @@ -49,6 +54,8 @@ struct QEMUVFIOState {
> int device;
> RAMBlockNotifier ram_notifier;
> struct vfio_region_info config_region_info, bar_region_info[6];
> + struct IOVARange *usable_iova_ranges;
> + uint8_t nb_iova_ranges;
>
> /* These fields are protected by @lock */
> /* VFIO's IO virtual address space is managed by splitting into a few
> @@ -236,6 +243,36 @@ static int qemu_vfio_pci_write_config(QEMUVFIOState *s,
> void *buf, int size, int
> return ret == size ? 0 : -errno;
> }
>
> +static void collect_usable_iova_ranges(QEMUVFIOState *s, void *first_cap)
> +{
> + struct vfio_iommu_type1_info_cap_iova_range *cap_iova_range;
> + struct vfio_info_cap_header *cap = first_cap;
> + void *offset = first_cap;
> + int i;
> +
> + while (cap->id != VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE) {
> + if (cap->next) {
This check looks reversed.
> + return;
> + }
> + offset += cap->next;
@offset is unused.
> + cap = (struct vfio_info_cap_header *)cap;
This assignment is nop.
> + }
> +
> + cap_iova_range = (struct vfio_iommu_type1_info_cap_iova_range *)cap;
> +
> + s->nb_iova_ranges = cap_iova_range->nr_iovas;
> + if (s->nb_iova_ranges > 1) {
> + s->usable_iova_ranges =
> + g_realloc(s->usable_iova_ranges,
> + s->nb_iova_ranges * sizeof(struct IOVARange));
> + }
> +
> + for (i = 0; i < s->nb_iova_ranges; i++) {
s/ / /
> + s->usable_iova_ranges[i].start =
> cap_iova_range->iova_ranges[i].start;
> + s->usable_iova_ranges[i].end = cap_iova_range->iova_ranges[i].end;
> + }
> +}
> +
> static int qemu_vfio_init_pci(QEMUVFIOState *s, const char *device,
> Error **errp)
> {
> @@ -243,10 +280,13 @@ static int qemu_vfio_init_pci(QEMUVFIOState *s, const
> char *device,
> int i;
> uint16_t pci_cmd;
> struct vfio_group_status group_status = { .argsz = sizeof(group_status)
> };
> - struct vfio_iommu_type1_info iommu_info = { .argsz = sizeof(iommu_info)
> };
> + struct vfio_iommu_type1_info *iommu_info = NULL;
> + size_t iommu_info_size = sizeof(*iommu_info);
> struct vfio_device_info device_info = { .argsz = sizeof(device_info) };
> char *group_file = NULL;
>
> + s->usable_iova_ranges = NULL;
> +
> /* Create a new container */
> s->container = open("/dev/vfio/vfio", O_RDWR);
>
> @@ -310,13 +350,38 @@ static int qemu_vfio_init_pci(QEMUVFIOState *s, const
> char *device,
> goto fail;
> }
>
> + iommu_info = g_malloc0(iommu_info_size);
> + iommu_info->argsz = iommu_info_size;
> +
> /* Get additional IOMMU info */
> - if (ioctl(s->container, VFIO_IOMMU_GET_INFO, &iommu_info)) {
> + if (ioctl(s->container, VFIO_IOMMU_GET_INFO, iommu_info)) {
> error_setg_errno(errp, errno, "Failed to get IOMMU info");
> ret = -errno;
> goto fail;
> }
>
> + /*
> + * if the kernel does not report usable IOVA regions, choose
> + * the legacy [QEMU_VFIO_IOVA_MIN, QEMU_VFIO_IOVA_MAX -1] region
> + */
> + s->nb_iova_ranges = 1;
> + s->usable_iova_ranges = g_new0(struct IOVARange, 1);
> + s->usable_iova_ranges[0].start = QEMU_VFIO_IOVA_MIN;
> + s->usable_iova_ranges[0].end = QEMU_VFIO_IOVA_MAX - 1;
> +
> + if (iommu_info->argsz > iommu_info_size) {
> + void *first_cap;
> +
> + iommu_info_size = iommu_info->argsz;
> + iommu_info = g_realloc(iommu_info, iommu_info_size);
> + if (ioctl(s->container, VFIO_IOMMU_GET_INFO, iommu_info)) {
> + ret = -errno;
> + goto fail;
> + }
> + first_cap = (void *)iommu_info + iommu_info->cap_offset;
> + collect_usable_iova_ranges(s, first_cap);
> + }
> +
> s->device = ioctl(s->group, VFIO_GROUP_GET_DEVICE_FD, device);
>
> if (s->device < 0) {
> @@ -365,8 +430,12 @@ static int qemu_vfio_init_pci(QEMUVFIOState *s, const
> char *device,
> if (ret) {
> goto fail;
> }
> + g_free(iommu_info);
> return 0;
> fail:
> + g_free(s->usable_iova_ranges);
Set s->usable_iova_ranges to NULL to avoid double free?
> + s->nb_iova_ranges = 0;
> + g_free(iommu_info);
> close(s->group);
> fail_container:
> close(s->container);
> @@ -716,6 +785,8 @@ void qemu_vfio_close(QEMUVFIOState *s)
> qemu_vfio_undo_mapping(s, &s->mappings[i], NULL);
> }
> ram_block_notifier_remove(&s->ram_notifier);
> + g_free(s->usable_iova_ranges);
> + s->nb_iova_ranges = 0;
> qemu_vfio_reset(s);
> close(s->device);
> close(s->group);
> --
> 2.21.3
>
>
Fam
[RFC 3/3] util/vfio-helpers: Rework the IOVA allocator to avoid IOVA reserved regions, Eric Auger, 2020/09/25