From 4937e604ca24c41cae3296d069c871c2f3f519c8 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 24 Jun 2025 14:52:28 +0200 Subject: [PATCH] scsi: core: Enforce unlimited max_segment_size when virt_boundary_mask is set The virt_boundary_mask limit requires an unlimited max_segment_size for bio splitting to not corrupt data. Historically, the block layer tried to validate this, although the check was half-hearted until the addition of the atomic queue limits API. The full blown check then triggered issues with stacked devices incorrectly inheriting limits such as the virt boundary and got disabled in commit b561ea56a264 ("block: allow device to have both virt_boundary_mask and max segment size") instead of fixing the issue properly. Ensure that the SCSI mid layer doesn't set the default low max_segment_size limit for this case, and check for invalid max_segment_size values in the host template, similar to the original block layer check given that SCSI devices can't be stacked. This fixes reported data corruption on storvsc, although as far as I can tell storvsc always failed to properly set the max_segment_size limit as the SCSI APIs historically applied that when setting up the host, while storvsc only set the virt_boundary_mask when configuring the scsi_device. Fixes: 81988a0e6b03 ("storvsc: get rid of bounce buffer") Fixes: b561ea56a264 ("block: allow device to have both virt_boundary_mask and max segment size") Reported-by: Ming Lei Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20250624125233.219635-3-hch@lst.de Reviewed-by: John Garry Reviewed-by: Ming Lei Reviewed-by: Hannes Reinecke Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/hosts.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index e021f1106bea..cc5d05dc395c 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -473,10 +473,17 @@ struct Scsi_Host *scsi_host_alloc(const struct scsi_host_template *sht, int priv else shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS; - if (sht->max_segment_size) - shost->max_segment_size = sht->max_segment_size; - else - shost->max_segment_size = BLK_MAX_SEGMENT_SIZE; + shost->virt_boundary_mask = sht->virt_boundary_mask; + if (shost->virt_boundary_mask) { + WARN_ON_ONCE(sht->max_segment_size && + sht->max_segment_size != UINT_MAX); + shost->max_segment_size = UINT_MAX; + } else { + if (sht->max_segment_size) + shost->max_segment_size = sht->max_segment_size; + else + shost->max_segment_size = BLK_MAX_SEGMENT_SIZE; + } /* 32-byte (dword) is a common minimum for HBAs. */ if (sht->dma_alignment) @@ -492,9 +499,6 @@ struct Scsi_Host *scsi_host_alloc(const struct scsi_host_template *sht, int priv else shost->dma_boundary = 0xffffffff; - if (sht->virt_boundary_mask) - shost->virt_boundary_mask = sht->virt_boundary_mask; - device_initialize(&shost->shost_gendev); dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); shost->shost_gendev.bus = &scsi_bus_type; -- 2.50.1