-----Original Message-----
> Date: Mon, 30 Jul 2018 11:59:06 +0100
> From: Anatoly Burakov <anatoly.bura...@intel.com>
> To: dev@dpdk.org
> CC: tho...@monjalon.net, jerin.ja...@caviumnetworks.com,
> t.yoshimura8...@gmail.com
> Subject: [PATCH] vfio: revert retry logic for MSI-X BAR mapping
> X-Mailer: git-send-email 1.7.0.7
>
> External Email
>
> This reverts commit d4774a568ba0a5923229974a002972c83eb04570.
>
> The patch is incomplete because kernel 4.16+, while being capable
> of mapping MSI-X BARs, will also report if such a capability is
> available. Without checking this capability, gratuitous errors
> are displayed on kernels <4.16 while VFIO is attempting to mmap
> MSI-X BAR and fails, which can be confusing to the user.
>
> Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
Acked-by: Jerin Jacob <jerin.ja...@caviumnetworks.com>
> ---
> drivers/bus/pci/linux/pci_vfio.c | 93 ++++++++++++++------------------
> 1 file changed, 41 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/bus/pci/linux/pci_vfio.c
> b/drivers/bus/pci/linux/pci_vfio.c
> index bb6ef7b67..686386d6a 100644
> --- a/drivers/bus/pci/linux/pci_vfio.c
> +++ b/drivers/bus/pci/linux/pci_vfio.c
> @@ -332,59 +332,50 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct
> mapped_pci_resource *vfio_res,
> void *bar_addr;
> struct pci_msix_table *msix_table = &vfio_res->msix_table;
> struct pci_map *bar = &vfio_res->maps[bar_index];
> - bool again = false;
>
> if (bar->size == 0)
> /* Skip this BAR */
> return 0;
>
> + if (msix_table->bar_index == bar_index) {
> + /*
> + * VFIO will not let us map the MSI-X table,
> + * but we can map around it.
> + */
> + uint32_t table_start = msix_table->offset;
> + uint32_t table_end = table_start + msix_table->size;
> + table_end = (table_end + ~PAGE_MASK) & PAGE_MASK;
> + table_start &= PAGE_MASK;
> +
> + if (table_start == 0 && table_end >= bar->size) {
> + /* Cannot map this BAR */
> + RTE_LOG(DEBUG, EAL, "Skipping BAR%d\n", bar_index);
> + bar->size = 0;
> + bar->addr = 0;
> + return 0;
> + }
> +
> + memreg[0].offset = bar->offset;
> + memreg[0].size = table_start;
> + memreg[1].offset = bar->offset + table_end;
> + memreg[1].size = bar->size - table_end;
> +
> + RTE_LOG(DEBUG, EAL,
> + "Trying to map BAR%d that contains the MSI-X "
> + "table. Trying offsets: "
> + "0x%04lx:0x%04lx, 0x%04lx:0x%04lx\n", bar_index,
> + memreg[0].offset, memreg[0].size,
> + memreg[1].offset, memreg[1].size);
> + } else {
> + memreg[0].offset = bar->offset;
> + memreg[0].size = bar->size;
> + }
> +
> /* reserve the address using an inaccessible mapping */
> bar_addr = mmap(bar->addr, bar->size, 0, MAP_PRIVATE |
> MAP_ANONYMOUS | additional_flags, -1, 0);
> - if (bar_addr == MAP_FAILED) {
> - RTE_LOG(ERR, EAL,
> - "Failed to create inaccessible mapping for BAR%d\n",
> - bar_index);
> - return -1;
> - }
> -
> - memreg[0].offset = bar->offset;
> - memreg[0].size = bar->size;
> - do {
> + if (bar_addr != MAP_FAILED) {
> void *map_addr = NULL;
> - if (again) {
> - /*
> - * VFIO did not let us map the MSI-X table,
> - * but we can map around it.
> - */
> - uint32_t table_start = msix_table->offset;
> - uint32_t table_end = table_start + msix_table->size;
> - table_end = (table_end + ~PAGE_MASK) & PAGE_MASK;
> - table_start &= PAGE_MASK;
> -
> - if (table_start == 0 && table_end >= bar->size) {
> - /* Cannot map this BAR */
> - RTE_LOG(DEBUG, EAL, "Skipping BAR%d\n",
> - bar_index);
> - munmap(bar_addr, bar->size);
> - bar->size = 0;
> - bar->addr = 0;
> - return 0;
> - }
> -
> - memreg[0].offset = bar->offset;
> - memreg[0].size = table_start;
> - memreg[1].offset = bar->offset + table_end;
> - memreg[1].size = bar->size - table_end;
> -
> - RTE_LOG(DEBUG, EAL,
> - "Trying to map BAR%d that contains the MSI-X "
> - "table. Trying offsets: "
> - "0x%04lx:0x%04lx, 0x%04lx:0x%04lx\n",
> bar_index,
> - memreg[0].offset, memreg[0].size,
> - memreg[1].offset, memreg[1].size);
> - }
> -
> if (memreg[0].size) {
> /* actual map of first part */
> map_addr = pci_map_resource(bar_addr, vfio_dev_fd,
> @@ -393,12 +384,6 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct
> mapped_pci_resource *vfio_res,
> MAP_FIXED);
> }
>
> - if (map_addr == MAP_FAILED &&
> - msix_table->bar_index == bar_index && !again) {
> - again = true;
> - continue;
> - }
> -
> /* if there's a second part, try to map it */
> if (map_addr != MAP_FAILED
> && memreg[1].offset && memreg[1].size) {
> @@ -419,8 +404,12 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct
> mapped_pci_resource *vfio_res,
> bar_index);
> return -1;
> }
> - break;
> - } while (again);
> + } else {
> + RTE_LOG(ERR, EAL,
> + "Failed to create inaccessible mapping for
> BAR%d\n",
> + bar_index);
> + return -1;
> + }
>
> bar->addr = bar_addr;
> return 0;
> --
> 2.17.1
