From 77a8884c44c212d61bd3523b862dabdd30bbb00f Mon Sep 17 00:00:00 2001 From: Hyong Youb Kim Date: Thu, 24 Sep 2020 19:14:35 -0700 Subject: [PATCH] bus/pci: fix mapping BAR containing MSI-X table When the BAR contains MSI-X table, pci_vfio_mmap_bar() tries to skip the table and map the rest. "map around it" is the phrase used in the source. The function splits the BAR into two regions: the region before the table (first part or memreg[0]) and the region after the table (second part or memreg[1]). For hardware that has MSI-X vector table offset 0, the first part does not exist (memreg[0].size == 0). Capabilities: [60] MSI-X: Enable- Count=48 Masked- Vector table: BAR=2 offset=00000000 PBA: BAR=2 offset=00001000 The mapping part of the function maps the first part, if it exists. Then, it maps the second part, if it exists and "if mapping the first part succeeded". The recent change that replaces MAP_FAILED with NULL breaks the "if mapping the first part succeeded" condition (1) in the snippet below. void *map_addr = NULL; if (memreg[0].size) { /* actual map of first part */ map_addr = pci_map_resource(...); } /* if there's a second part, try to map it */ if (map_addr != NULL // -- (1) && memreg[1].offset && memreg[1].size) { [...] } if (map_addr == NULL) { RTE_LOG(ERR, EAL, "Failed to map pci BAR%d\n", bar_index); return -1; } When the first part does not exist, (1) sees map_addr is still NULL, and the function fails. This behavior is a regression and fails probing hardware with vector table offset 0. Previously, (1) was "map_addr != MAP_FAILED", which meant pci_map_resource() was actually attempted and failed. So, expand (1) to check if the first part exists as well, to match the semantics of MAP_FAILED. Bugzilla ID: 539 Fixes: e200535c1ca3 ("mem: drop mapping API workaround") Signed-off-by: Hyong Youb Kim Acked-by: Anatoly Burakov --- drivers/bus/pci/linux/pci_vfio.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c index 34b5da80df..d2073994fa 100644 --- a/drivers/bus/pci/linux/pci_vfio.c +++ b/drivers/bus/pci/linux/pci_vfio.c @@ -564,8 +564,20 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct mapped_pci_resource *vfio_res, RTE_MAP_FORCE_ADDRESS); } + /* + * Regarding "memreg[0].size == 0": + * If this BAR has MSI-X table, memreg[0].size (the + * first part or the part before the table) can + * legitimately be 0 for hardware using vector table + * offset 0 (i.e. first part does not exist). + * + * When memreg[0].size is 0, "mapping the first part" + * never happens, and map_addr is NULL at this + * point. So check that mapping has been actually + * attempted. + */ /* if there's a second part, try to map it */ - if (map_addr != NULL + if ((map_addr != NULL || memreg[0].size == 0) && memreg[1].offset && memreg[1].size) { void *second_addr = RTE_PTR_ADD(bar_addr, (uintptr_t)(memreg[1].offset - -- 2.20.1