2 files changed, 18 insertions, 2 deletions

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index b8bd936374f2..d890679e4c4d 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -1054,6 +1054,7 @@ static int efx_init_io(struct efx_nic *efx)
 {
         struct pci_dev *pci_dev = efx->pci_dev;
         dma_addr_t dma_mask = efx->type->max_dma_mask;
+        bool use_wc;
         int rc;
 
         netif_dbg(efx, probe, efx->net_dev, "initialising I/O\n");
@@ -1104,8 +1105,21 @@ static int efx_init_io(struct efx_nic *efx)
                 rc = -EIO;
                 goto fail3;
         }
-        efx->membase = ioremap_wc(efx->membase_phys,
-                                  efx->type->mem_map_size);
+
+        /* bug22643: If SR-IOV is enabled then tx push over a write combined
+         * mapping is unsafe. We need to disable write combining in this case.
+         * MSI is unsupported when SR-IOV is enabled, and the firmware will
+         * have removed the MSI capability. So write combining is safe if
+         * there is an MSI capability.
+         */
+        use_wc = (!EFX_WORKAROUND_22643(efx) ||
+                  pci_find_capability(pci_dev, PCI_CAP_ID_MSI));
+        if (use_wc)
+                efx->membase = ioremap_wc(efx->membase_phys,
+                                          efx->type->mem_map_size);
+        else
+                efx->membase = ioremap_nocache(efx->membase_phys,
+                                               efx->type->mem_map_size);
         if (!efx->membase) {
                 netif_err(efx, probe, efx->net_dev,
                           "could not map memory BAR at %llx+%x\n",
diff --git a/drivers/net/sfc/workarounds.h b/drivers/net/sfc/workarounds.h
index e4dd3a7f304b..99ff11400cef 100644
--- a/drivers/net/sfc/workarounds.h
+++ b/drivers/net/sfc/workarounds.h
@@ -38,6 +38,8 @@
 #define EFX_WORKAROUND_15783 EFX_WORKAROUND_ALWAYS
 /* Legacy interrupt storm when interrupt fifo fills */
 #define EFX_WORKAROUND_17213 EFX_WORKAROUND_SIENA
+/* Write combining and sriov=enabled are incompatible */
+#define EFX_WORKAROUND_22643 EFX_WORKAROUND_SIENA
 
 /* Spurious parity errors in TSORT buffers */
 #define EFX_WORKAROUND_5129 EFX_WORKAROUND_FALCON_A