PCI: epf-test: Fix DMA transfer completion detection

pci_epf_test_data_transfer() and pci_epf_test_dma_callback() are not
handling DMA transfer completion correctly, leading to completion
notifications to the RC side that are too early. This problem can be
detected when the RC side is running an IOMMU with messages such as:

  pci-endpoint-test 0000:0b:00.0: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x001c address=0xfff00000 flags=0x0000]

When running the pcitest.sh tests: the address used for a previous
test transfer generates the above error while the next test transfer is
running.

Fix this by testing the DMA transfer status in pci_epf_test_dma_callback()
and notifying the completion only when the transfer status is DMA_COMPLETE
or DMA_ERROR. Furthermore, in pci_epf_test_data_transfer(), be paranoid and
check again the transfer status and always call dmaengine_terminate_sync()
before returning.

Link: https://lore.kernel.org/r/20230415023542.77601-5-dlemoal@kernel.org
Fixes: 8353813c88ef ("PCI: endpoint: Enable DMA tests for endpoints with DMA capabilities")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index d654197..dbea6eb 100644 (file)
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -54,6 +54,9 @@ struct pci_epf_test {
        struct delayed_work     cmd_handler;
        struct dma_chan         *dma_chan_tx;
        struct dma_chan         *dma_chan_rx;
+       struct dma_chan         *transfer_chan;
+       dma_cookie_t            transfer_cookie;
+       enum dma_status         transfer_status;
        struct completion       transfer_complete;
        bool                    dma_supported;
        bool                    dma_private;
@@ -85,8 +88,14 @@ static size_t bar_size[] = { 512, 512, 1024, 16384, 131072, 1048576 };
 static void pci_epf_test_dma_callback(void *param)
 {
        struct pci_epf_test *epf_test = param;
-
-       complete(&epf_test->transfer_complete);
+       struct dma_tx_state state;
+
+       epf_test->transfer_status =
+               dmaengine_tx_status(epf_test->transfer_chan,
+                                   epf_test->transfer_cookie, &state);
+       if (epf_test->transfer_status == DMA_COMPLETE ||
+           epf_test->transfer_status == DMA_ERROR)
+               complete(&epf_test->transfer_complete);
 }
 
 /**
@@ -120,7 +129,6 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
        struct dma_async_tx_descriptor *tx;
        struct dma_slave_config sconf = {};
        struct device *dev = &epf->dev;
-       dma_cookie_t cookie;
        int ret;
 
        if (IS_ERR_OR_NULL(chan)) {
@@ -152,25 +160,33 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
        }
 
        reinit_completion(&epf_test->transfer_complete);
+       epf_test->transfer_chan = chan;
        tx->callback = pci_epf_test_dma_callback;
        tx->callback_param = epf_test;
-       cookie = tx->tx_submit(tx);
+       epf_test->transfer_cookie = tx->tx_submit(tx);
 
-       ret = dma_submit_error(cookie);
+       ret = dma_submit_error(epf_test->transfer_cookie);
        if (ret) {
-               dev_err(dev, "Failed to do DMA tx_submit %d\n", cookie);
-               return -EIO;
+               dev_err(dev, "Failed to do DMA tx_submit %d\n", ret);
+               goto terminate;
        }
 
        dma_async_issue_pending(chan);
        ret = wait_for_completion_interruptible(&epf_test->transfer_complete);
        if (ret < 0) {
-               dmaengine_terminate_sync(chan);
-               dev_err(dev, "DMA wait_for_completion_timeout\n");
-               return -ETIMEDOUT;
+               dev_err(dev, "DMA wait_for_completion interrupted\n");
+               goto terminate;
        }
 
-       return 0;
+       if (epf_test->transfer_status == DMA_ERROR) {
+               dev_err(dev, "DMA transfer failed\n");
+               ret = -EIO;
+       }
+
+terminate:
+       dmaengine_terminate_sync(chan);
+
+       return ret;
 }
 
 struct epf_dma_filter {