* [PATCH v5 1/5] vfio: selftests: igb: Add driver for Intel 82576 device
2026-07-14 20:57 [PATCH v5 0/5] vfio: selftests: Add driver for Intel Ethernet Gigabit Controller (IGB) Josh Hilke
@ 2026-07-14 20:57 ` Josh Hilke
2026-07-14 21:28 ` sashiko-bot
2026-07-14 20:57 ` [PATCH v5 2/5] vfio: selftests: igb: Use PHY internal loopback on 82576 Josh Hilke
` (3 subsequent siblings)
4 siblings, 1 reply; 8+ messages in thread
From: Josh Hilke @ 2026-07-14 20:57 UTC (permalink / raw)
To: David Matlack, Alex Williamson
Cc: Shuah Khan, linux-kernel, kvm, linux-kselftest, Vipin Sharma,
Josh Hilke, Alex Williamson
Add a VFIO selftest driver for the Intel Gigabit Ethernet controller
(IGB), specifically targeting the 82576 device. IGB is fully
virtualized in QEMU which makes it easy to run VFIO selftests without
needing any specific hardware.
The driver uses advanced descriptors for transmit and receive,
configuring SRRCTL.DESCTYPE to the advanced one-buffer layout for
receive and advanced data descriptor fields in igb_memcpy_start() for
transmit.
It also programs the full MSI-X routing sequence:
- GPIE.Multiple_MSIX to route causes through IVAR.
- GPIE.EIAME to apply EIAM on MSI-X assertion.
- EIAC to enable auto-clear of EICR for vector 0.
- EIAM to enable auto-mask of EIMS for vector 0 on MSI-X assertion.
- IVAR to map RX cause 0 to MSI-X vector 0.
Write-to-clear is used for EICR as required when EIAC is enabled.
To support real 82576 hardware which processes the descriptor ring at
line rate, the memcpy completion timeout in igb_memcpy_wait() is set
to 200 ms (200 retries of 1ms). At 1 Gb/s (~125 MB/s) the worst valid
memcpy (~4 MB) takes ~32 ms on the wire, plus overhead (~3%) and latency.
A 200 ms timeout leaves comfortable headroom for host scheduling jitter
while keeping intentional invalid-DMA tests bounded.
Additionally, DMA re-send on PCIe completion timeout is disabled by
clearing GCR.Completion_Timeout_Resend (datasheet section 8.6.1, bit 16).
The mix_and_match test intentionally submits descriptors targeting
unmapped IOVAs; with the default value, the device retries the failed
read indefinitely, which keeps PCIe AER and IOMMU error handling busy
and interferes with reset recovery.
Co-developed-by: Alex Williamson <alex.williamson@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
Signed-off-by: Josh Hilke <jrhilke@google.com>
---
.../selftests/vfio/lib/drivers/igb/e1000_82575.h | 1 +
.../selftests/vfio/lib/drivers/igb/e1000_defines.h | 1 +
.../selftests/vfio/lib/drivers/igb/e1000_regs.h | 1 +
tools/testing/selftests/vfio/lib/drivers/igb/igb.c | 475 +++++++++++++++++++++
tools/testing/selftests/vfio/lib/libvfio.mk | 1 +
tools/testing/selftests/vfio/lib/vfio_pci_driver.c | 2 +
6 files changed, 481 insertions(+)
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/e1000_82575.h b/tools/testing/selftests/vfio/lib/drivers/igb/e1000_82575.h
new file mode 120000
index 000000000000..b84affdec559
--- /dev/null
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/e1000_82575.h
@@ -0,0 +1 @@
+../../../../../../../drivers/net/ethernet/intel/igb/e1000_82575.h
\ No newline at end of file
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/e1000_defines.h b/tools/testing/selftests/vfio/lib/drivers/igb/e1000_defines.h
new file mode 120000
index 000000000000..9f97f4330086
--- /dev/null
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/e1000_defines.h
@@ -0,0 +1 @@
+../../../../../../../drivers/net/ethernet/intel/igb/e1000_defines.h
\ No newline at end of file
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/e1000_regs.h b/tools/testing/selftests/vfio/lib/drivers/igb/e1000_regs.h
new file mode 120000
index 000000000000..c733634171bb
--- /dev/null
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/e1000_regs.h
@@ -0,0 +1 @@
+../../../../../../../drivers/net/ethernet/intel/igb/e1000_regs.h
\ No newline at end of file
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
new file mode 100644
index 000000000000..a59b95303092
--- /dev/null
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
@@ -0,0 +1,475 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <unistd.h>
+#include <errno.h>
+#include <stdint.h>
+#include <linux/io.h>
+#include <linux/pci_regs.h>
+#include <linux/pci_ids.h>
+#include <linux/kernel.h>
+#include <linux/compiler.h>
+#include <asm/barrier.h>
+#include <linux/mii.h>
+#include <libvfio/vfio_pci_device.h>
+
+#include "e1000_regs.h"
+#include "e1000_defines.h"
+#include "e1000_82575.h"
+
+#define PCI_DEVICE_ID_INTEL_82576 0x10C9
+#define IGB_MAX_CHUNK_SIZE 1024
+#define MSIX_VECTOR 0
+#define MSIX_VECTOR_MASK (1 << MSIX_VECTOR)
+#define RING_SIZE 4096 /* Number of descriptors in ring */
+
+struct igb_tx_desc {
+ union {
+ struct {
+ u64 buffer_addr; /* Address of descriptor's data buffer */
+ u32 cmd_type_len; /* Command/Type/Length */
+ u32 olinfo_status; /* Context/Buffer info */
+ } read;
+
+ struct {
+ u64 rsvd; /* Reserved */
+ u32 nxtseq_seed; /* Next sequence seed */
+ u32 status; /* Descriptor status */
+ } wb;
+ };
+};
+
+struct igb_rx_desc {
+ union {
+ struct {
+ u64 pkt_addr; /* Packet buffer address */
+ u64 hdr_addr; /* Header buffer address */
+ } read;
+ struct {
+ u16 pkt_info; /* RSS type, Packet type */
+ u16 hdr_info; /* Split Head, buf len */
+ u32 rss; /* RSS Hash */
+ u32 status_error; /* ext status/error */
+ u16 length; /* Packet length */
+ u16 vlan; /* VLAN tag */
+ } wb; /* writeback */
+ };
+};
+
+struct igb {
+ void *bar0;
+ u32 tx_tail;
+ u32 rx_tail;
+ struct igb_tx_desc tx_ring[RING_SIZE] __attribute__((aligned(128)));
+ struct igb_rx_desc rx_ring[RING_SIZE] __attribute__((aligned(128)));
+};
+
+static inline struct igb *to_igb_state(struct vfio_pci_device *device)
+{
+ return (struct igb *)device->driver.region.vaddr;
+}
+
+static inline void igb_write32(struct igb *igb, u32 reg, u32 val)
+{
+ writel(val, igb->bar0 + reg);
+}
+
+static inline u32 igb_read32(struct igb *igb, u32 reg)
+{
+ return readl(igb->bar0 + reg);
+}
+
+static int igb_write_phy(struct igb *igb, u32 offset, u16 data)
+{
+ u32 mdic;
+ int i;
+
+ /*
+ * Write a PHY register over MDIO.
+ *
+ * A production driver would hold the SW/FW semaphore (SWSM.SWESMBI + the
+ * SW_FW_SYNC PHY bit) across the MDIO transaction to serialize against the
+ * device's management firmware. The selftest owns the assigned function
+ * exclusively on a dedicated test device with no active manageability
+ * contending for the PHY, so the sync is omitted; it should be added here
+ * if this ever needs to run on a manageability-enabled NIC.
+ */
+ mdic = (((u32)data) |
+ (offset << E1000_MDIC_REG_SHIFT) |
+ (1 << E1000_MDIC_PHY_SHIFT) |
+ E1000_MDIC_OP_WRITE);
+
+ igb_write32(igb, E1000_MDIC, mdic);
+
+ for (i = 0; i < 1000; i++) {
+ usleep(50);
+ mdic = igb_read32(igb, E1000_MDIC);
+ if (mdic & E1000_MDIC_READY)
+ break;
+ }
+
+ if (!(mdic & E1000_MDIC_READY))
+ return -1;
+
+ if (mdic & E1000_MDIC_ERROR)
+ return -1;
+
+ return 0;
+}
+
+static int igb_read_phy(struct igb *igb, u32 offset, u16 *data)
+{
+ u32 mdic;
+ int i;
+
+ mdic = ((offset << E1000_MDIC_REG_SHIFT) |
+ (1 << E1000_MDIC_PHY_SHIFT) |
+ E1000_MDIC_OP_READ);
+
+ igb_write32(igb, E1000_MDIC, mdic);
+
+ for (i = 0; i < 1000; i++) {
+ usleep(50);
+ mdic = igb_read32(igb, E1000_MDIC);
+ if (mdic & E1000_MDIC_READY)
+ break;
+ }
+
+ if (!(mdic & E1000_MDIC_READY))
+ return -1;
+
+ if (mdic & E1000_MDIC_ERROR)
+ return -1;
+
+ *data = (u16)mdic;
+ return 0;
+}
+
+static void igb_phy_setup_autoneg(struct igb *igb)
+{
+ int timeout_ms = 1000;
+ bool success = false;
+ u16 phy_status;
+ int ret;
+ int i;
+
+ /* Trigger auto-negotiation */
+ ret = igb_write_phy(igb, MII_BMCR,
+ BMCR_ANENABLE | BMCR_ANRESTART);
+ VFIO_ASSERT_EQ(ret, 0, "Failed to write PHY control register");
+
+ for (i = 0; i < timeout_ms; i++) {
+ if (igb_read_phy(igb, MII_BMSR, &phy_status) == 0) {
+ success = !!(phy_status & BMSR_ANEGCOMPLETE);
+ if (success)
+ break;
+ }
+ usleep(1000);
+ }
+
+ VFIO_ASSERT_TRUE(success, "Auto-negotiation did not complete in time");
+}
+
+static int igb_probe(struct vfio_pci_device *device)
+{
+ if (!vfio_pci_device_match(device, PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82576))
+ return -EINVAL;
+
+ return 0;
+}
+
+static void igb_reset(struct igb *igb)
+{
+ igb_write32(igb, E1000_CTRL, igb_read32(igb, E1000_CTRL) | E1000_CTRL_RST);
+ /*
+ * Must wait at least 1 millisecond after setting the reset bit before
+ * checking if this device is ready to be used (82576 datasheet section
+ * 4.2.1.6.1).
+ */
+ usleep(2000);
+ VFIO_ASSERT_EQ(igb_read32(igb, E1000_CTRL) & E1000_CTRL_RST, 0);
+ igb_write32(igb, E1000_IMC, 0xFFFFFFFF);
+}
+
+static void igb_init(struct vfio_pci_device *device)
+{
+ struct igb *igb = to_igb_state(device);
+ u64 iova_tx, iova_rx;
+ u32 ctrl, rctl;
+ u16 cmd_reg;
+ int retries;
+
+ VFIO_ASSERT_GE(device->driver.region.size, sizeof(struct igb));
+
+ /* Set up rings and calculate IOVAs */
+ igb->bar0 = device->bars[0].vaddr;
+
+ iova_tx = to_iova(device, igb->tx_ring);
+ iova_rx = to_iova(device, igb->rx_ring);
+
+ igb_reset(igb);
+
+ /* Signal that the driver is loaded */
+ ctrl = igb_read32(igb, E1000_CTRL_EXT);
+ ctrl |= E1000_CTRL_EXT_DRV_LOAD;
+ ctrl &= ~E1000_CTRL_EXT_LINK_MODE_MASK;
+ igb_write32(igb, E1000_CTRL_EXT, ctrl);
+
+ /* Enable PCI Bus Master. */
+ cmd_reg = vfio_pci_config_readw(device, PCI_COMMAND);
+ if ((cmd_reg & (PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY)) !=
+ (PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY)) {
+ cmd_reg |= (PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY);
+ vfio_pci_config_writew(device, PCI_COMMAND, cmd_reg);
+ }
+
+ /* Trigger autonegotiation. This enables IGB to transmit data. */
+ igb_phy_setup_autoneg(igb);
+
+ /*
+ * Disable DMA re-send on PCIe completion timeout (82576 datasheet
+ * section 8.6.1, GCR.Completion_Timeout_Resend, bit 16). The
+ * mix_and_match test intentionally submits descriptors targeting
+ * unmapped IOVAs; with the default (set) value, the device keeps
+ * retrying the failed read indefinitely, which keeps PCIe AER and
+ * IOMMU error handling busy and interferes with reset recovery.
+ */
+ ctrl = igb_read32(igb, E1000_GCR);
+ ctrl &= ~E1000_GCR_CMPL_TMOUT_RESEND;
+ igb_write32(igb, E1000_GCR, ctrl);
+
+ /* Configure TX and RX descriptor rings */
+ igb_write32(igb, E1000_TDBAL(0), (u32)iova_tx);
+ igb_write32(igb, E1000_TDBAH(0), (u32)(iova_tx >> 32));
+ igb_write32(igb, E1000_TDLEN(0), RING_SIZE * sizeof(struct igb_tx_desc));
+ igb_write32(igb, E1000_TDH(0), 0);
+ igb_write32(igb, E1000_TDT(0), 0);
+ igb_write32(igb, E1000_TXDCTL(0), E1000_TXDCTL_QUEUE_ENABLE);
+
+ igb_write32(igb, E1000_RDBAL(0), (u32)iova_rx);
+ igb_write32(igb, E1000_RDBAH(0), (u32)(iova_rx >> 32));
+ igb_write32(igb, E1000_RDLEN(0), RING_SIZE * sizeof(struct igb_rx_desc));
+ igb_write32(igb, E1000_RDH(0), 0);
+ igb_write32(igb, E1000_RDT(0), 0);
+
+ /*
+ * Select the advanced one-buffer descriptor format. Per 82576
+ * datasheet section 7.1.5.2: "SRRCTL[n].DESCTYPE must be set to a
+ * value other than 000b for the 82576 to write back the special
+ * descriptors." struct igb_rx_desc matches the advanced one-buffer
+ * writeback layout (section 7.1.5.2), so polling rx.wb.status_error
+ * requires this format. Section 8.10.2 specifies DESCTYPE[27:25].
+ *
+ * The direct write also zeroes SRRCTL.BSIZEPACKET, which is
+ * intentional: per section 7.1.3.1 a zero BSIZEPACKET falls back to
+ * the RCTL.BSIZE buffer size, whose reset default (00b) is 2048
+ * bytes -- ample for the loopback frames here.
+ */
+ igb_write32(igb, E1000_SRRCTL(0), E1000_SRRCTL_DESCTYPE_ADV_ONEBUF);
+
+ igb_write32(igb, E1000_RXDCTL(0), E1000_RXDCTL_QUEUE_ENABLE);
+
+ /* Wait for TX and RX queues to be enabled */
+ retries = 2000;
+ while (retries-- > 0) {
+ if ((igb_read32(igb, E1000_TXDCTL(0)) & E1000_TXDCTL_QUEUE_ENABLE) &&
+ (igb_read32(igb, E1000_RXDCTL(0)) & E1000_RXDCTL_QUEUE_ENABLE))
+ break;
+ usleep(10);
+ }
+ VFIO_ASSERT_GE(retries, 0);
+
+ /* Enable Receiver and Transmitter */
+ rctl = E1000_RCTL_EN | /* Receiver Enable */
+ E1000_RCTL_UPE | /* Unicast Promiscuous (for dummy MAC) */
+ E1000_RCTL_MPE | /* Multicast Promiscuous */
+ E1000_RCTL_BAM | /* Broadcast Accept Mode */
+ E1000_RCTL_LBM_MAC | /* MAC Loopback Mode */
+ E1000_RCTL_SECRC; /* Strip CRC (needed for memcmp) */
+ igb_write32(igb, E1000_RCTL, rctl);
+ igb_write32(igb, E1000_TCTL, E1000_TCTL_EN);
+
+ /* Enable MSI-X with 1 vector for the test */
+ vfio_pci_msix_enable(device, MSIX_VECTOR, 1);
+
+ /*
+ * Program MSI-X interrupt routing per 82576 datasheet:
+ *
+ * GPIE (section 7.3.2.11, Table 7-47): set Multiple_MSIX (bit 4) to
+ * route interrupt causes through IVAR mapping, and EIAME (bit 30)
+ * to apply EIAM on MSI-X assertion (without EIAME, EIAM only
+ * applies on EICR read/write).
+ *
+ * EIAC (section 8.8.5): enable auto-clear of EICR for vector 0.
+ * Without auto-clear the cause stays set after delivery and the
+ * test can see spurious interrupts on the next memcpy batch.
+ *
+ * EIAM (section 8.8.6): enable auto-mask of EIMS for vector 0 on
+ * MSI-X assertion (effective because EIAME is set), so a single
+ * interrupt is delivered per memcpy batch even if the cause
+ * re-asserts before software re-enables the mask.
+ *
+ * IVAR (section 7.3.1.2, register definition in 8.8.13): map RX
+ * cause 0 to MSI-X vector 0 and mark the entry valid.
+ */
+ igb_write32(igb, E1000_GPIE, E1000_GPIE_MSIX_MODE | E1000_GPIE_EIAME);
+ igb_write32(igb, E1000_EIAC, MSIX_VECTOR_MASK);
+ igb_write32(igb, E1000_EIAM, MSIX_VECTOR_MASK);
+
+ /* Map vector 0 to interrupt cause 0 and mark it valid */
+ igb_write32(igb, E1000_IVAR0, E1000_IVAR_VALID);
+
+ /* Enable interrupts on vector 0 */
+ igb_write32(igb, E1000_EIMS, MSIX_VECTOR_MASK);
+
+ /* Initialize driver state and capability limits */
+ igb->tx_tail = 0;
+ igb->rx_tail = 0;
+
+ device->driver.max_memcpy_size = IGB_MAX_CHUNK_SIZE;
+ device->driver.max_memcpy_count = RING_SIZE - 1;
+ device->driver.msi = MSIX_VECTOR;
+}
+
+static void igb_remove(struct vfio_pci_device *device)
+{
+ struct igb *igb = to_igb_state(device);
+
+ igb_write32(igb, E1000_RCTL, 0);
+ igb_write32(igb, E1000_TCTL, 0);
+ igb_reset(igb);
+
+ vfio_pci_msix_disable(device);
+}
+
+static void igb_irq_disable(struct igb *igb)
+{
+ igb_write32(igb, E1000_EIMC, MSIX_VECTOR_MASK);
+}
+
+static void igb_irq_enable(struct igb *igb)
+{
+ igb_write32(igb, E1000_EIMS, MSIX_VECTOR_MASK);
+}
+
+static void igb_irq_clear(struct igb *igb)
+{
+ /*
+ * Use write-to-clear (datasheet 7.3.4.2). In MSI-X mode with EIAC
+ * programmed, section 8.8.5 explicitly states "If any bits are set
+ * in EIAC, the EICR register should not be read", which rules out
+ * the read-to-clear path in 7.3.4.3. Bits not in EIAC are still
+ * cleared by writing 1.
+ */
+ igb_write32(igb, E1000_EICR, 0xFFFFFFFF);
+}
+
+static void igb_memcpy_start(struct vfio_pci_device *device, iova_t src,
+ iova_t dst, u64 size, u64 count)
+{
+ struct igb *igb = to_igb_state(device);
+ struct igb_rx_desc *rx;
+ struct igb_tx_desc *tx;
+ u32 i;
+
+ igb_irq_disable(igb);
+
+ for (i = 0; i < count; i++) {
+ tx = &igb->tx_ring[igb->tx_tail];
+ rx = &igb->rx_ring[igb->rx_tail];
+
+ memset(tx, 0, sizeof(struct igb_tx_desc));
+ memset(rx, 0, sizeof(struct igb_rx_desc));
+
+ rx->read.pkt_addr = cpu_to_le64(dst);
+ rx->read.hdr_addr = cpu_to_le64(0);
+
+ tx->read.buffer_addr = cpu_to_le64(src);
+ /*
+ * Build an advanced data descriptor per 82576 datasheet
+ * section 7.2.2.3. DEXT marks the descriptor as advanced
+ * (required by hardware); DTYP=data selects the data
+ * descriptor; IFCS asks the MAC to append the Ethernet
+ * FCS (without it the frame is dropped as malformed);
+ * EOP marks end of packet. DTALEN is the buffer length
+ * in bits 15:0 of cmd_type_len.
+ */
+ tx->read.cmd_type_len = cpu_to_le32((uint32_t)size |
+ E1000_ADVTXD_DTYP_DATA |
+ E1000_ADVTXD_DCMD_DEXT |
+ E1000_ADVTXD_DCMD_IFCS |
+ E1000_ADVTXD_DCMD_EOP);
+ /*
+ * PAYLEN (section 7.2.2.3.11) is the total payload size
+ * in olinfo_status[31:14].
+ */
+ tx->read.olinfo_status =
+ cpu_to_le32((uint32_t)size << E1000_ADVTXD_PAYLEN_SHIFT);
+
+ igb->tx_tail = (igb->tx_tail + 1) % RING_SIZE;
+ igb->rx_tail = (igb->rx_tail + 1) % RING_SIZE;
+ }
+
+ igb_write32(igb, E1000_RDT(0), igb->rx_tail);
+ igb_write32(igb, E1000_TDT(0), igb->tx_tail);
+}
+
+static int igb_memcpy_wait(struct vfio_pci_device *device)
+{
+ struct igb *igb = to_igb_state(device);
+ struct igb_rx_desc *rx;
+ u32 status = 0;
+ u32 prev_tail;
+ int retries;
+
+ prev_tail = (igb->rx_tail + RING_SIZE - 1) % RING_SIZE;
+ rx = &igb->rx_ring[prev_tail];
+
+ /*
+ * Real 82576 hardware processes the descriptor ring at line rate.
+ * max_memcpy_size = (RING_SIZE - 1) * IGB_MAX_CHUNK_SIZE ~= 4 MB,
+ * split into 4095 1 KB frames. At 1 Gb/s (~125 MB/s) the worst
+ * valid memcpy takes ~32 ms on the wire, plus per-frame preamble,
+ * SFD, IFG and FCS overhead (~3%) and descriptor fetch/writeback
+ * latency. Wait up to ~200 ms before declaring the device hung;
+ * ~6x the line-rate floor leaves comfortable headroom for host
+ * scheduling jitter while keeping the intentional invalid-DMA
+ * tests bounded.
+ */
+ retries = 200;
+ while (retries-- > 0) {
+ status = le32_to_cpu(READ_ONCE(rx->wb.status_error));
+ if (status & 1)
+ break;
+ usleep(1000);
+ }
+
+ if (status & 1)
+ /*
+ * Ensure the test code doesn't speculatively read the DMA
+ * destination buffer before we have verified that the
+ * descriptor writeback is complete.
+ */
+ rmb();
+
+ igb_irq_clear(igb);
+
+ igb_irq_enable(igb);
+
+ return (status & 1) ? 0 : -ETIMEDOUT;
+}
+
+static void igb_send_msi(struct vfio_pci_device *device)
+{
+ struct igb *igb = to_igb_state(device);
+
+ igb_write32(igb, E1000_EICS, MSIX_VECTOR_MASK);
+}
+
+const struct vfio_pci_driver_ops igb_ops = {
+ .name = "igb",
+ .probe = igb_probe,
+ .init = igb_init,
+ .remove = igb_remove,
+ .memcpy_start = igb_memcpy_start,
+ .memcpy_wait = igb_memcpy_wait,
+ .send_msi = igb_send_msi,
+};
diff --git a/tools/testing/selftests/vfio/lib/libvfio.mk b/tools/testing/selftests/vfio/lib/libvfio.mk
index 9f47bceed16f..1f13cca04348 100644
--- a/tools/testing/selftests/vfio/lib/libvfio.mk
+++ b/tools/testing/selftests/vfio/lib/libvfio.mk
@@ -12,6 +12,7 @@ LIBVFIO_C += vfio_pci_driver.c
ifeq ($(ARCH:x86_64=x86),x86)
LIBVFIO_C += drivers/ioat/ioat.c
LIBVFIO_C += drivers/dsa/dsa.c
+LIBVFIO_C += drivers/igb/igb.c
endif
LIBVFIO_OUTPUT := $(OUTPUT)/libvfio
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_driver.c b/tools/testing/selftests/vfio/lib/vfio_pci_driver.c
index 6827f4a6febe..a5d0547132c4 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_driver.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_driver.c
@@ -5,12 +5,14 @@
#ifdef __x86_64__
extern struct vfio_pci_driver_ops dsa_ops;
extern struct vfio_pci_driver_ops ioat_ops;
+extern struct vfio_pci_driver_ops igb_ops;
#endif
static struct vfio_pci_driver_ops *driver_ops[] = {
#ifdef __x86_64__
&dsa_ops,
&ioat_ops,
+ &igb_ops,
#endif
};
--
2.55.0.141.g00534a21ce-goog
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH v5 1/5] vfio: selftests: igb: Add driver for Intel 82576 device
2026-07-14 20:57 ` [PATCH v5 1/5] vfio: selftests: igb: Add driver for Intel 82576 device Josh Hilke
@ 2026-07-14 21:28 ` sashiko-bot
0 siblings, 0 replies; 8+ messages in thread
From: sashiko-bot @ 2026-07-14 21:28 UTC (permalink / raw)
To: Josh Hilke; +Cc: kvm
Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The selftest relies on external PHY auto-negotiation, which will cause the test to fail on real hardware if no physical link (cable) is connected.
- [Medium] MMIO registers are accessed before PCI memory space is enabled, which can crash the test if memory space is disabled.
--
--- Patch [1]: [PATCH v5 1/5] vfio: selftests: igb: Add driver for Intel 82576 device ---
commit b66293558b628d9af7dfd3c68ff9a1e69b1cbb0b
Author: Josh Hilke <jrhilke@google.com>
vfio: selftests: igb: Add driver for Intel 82576 device
Add a VFIO selftest driver for the Intel Gigabit Ethernet controller
(IGB), specifically targeting the 82576 device. IGB is fully
virtualized in QEMU which makes it easy to run VFIO selftests without
needing any specific hardware.
> diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
> new file mode 100644
> index 0000000000000..a59b953030925
> --- /dev/null
> +++ b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
[ ... ]
> +static void igb_phy_setup_autoneg(struct igb *igb)
> +{
> + int timeout_ms = 1000;
> + bool success = false;
> + u16 phy_status;
> + int ret;
> + int i;
> +
> + /* Trigger auto-negotiation */
> + ret = igb_write_phy(igb, MII_BMCR,
> + BMCR_ANENABLE | BMCR_ANRESTART);
> + VFIO_ASSERT_EQ(ret, 0, "Failed to write PHY control register");
> +
> + for (i = 0; i < timeout_ms; i++) {
> + if (igb_read_phy(igb, MII_BMSR, &phy_status) == 0) {
> + success = !!(phy_status & BMSR_ANEGCOMPLETE);
> + if (success)
> + break;
> + }
> + usleep(1000);
> + }
> +
> + VFIO_ASSERT_TRUE(success, "Auto-negotiation did not complete in time");
[Severity: Medium]
Will this cause the selftest to fail on real hardware if no physical cable is
connected?
Since this relies on external PHY auto-negotiation, it looks like the
BMSR_ANEGCOMPLETE bit will never set without a physical link partner,
triggering this assertion failure.
[ ... ]
> +static void igb_reset(struct igb *igb)
> +{
> + igb_write32(igb, E1000_CTRL, igb_read32(igb, E1000_CTRL) | E1000_CTRL_RST);
> + /*
> + * Must wait at least 1 millisecond after setting the reset bit before
> + * checking if this device is ready to be used (82576 datasheet section
> + * 4.2.1.6.1).
> + */
> + usleep(2000);
> + VFIO_ASSERT_EQ(igb_read32(igb, E1000_CTRL) & E1000_CTRL_RST, 0);
[Severity: Medium]
Can this assertion fail due to igb_read32() returning 0xFFFFFFFF if PCI
memory space is disabled?
[ ... ]
> +static void igb_init(struct vfio_pci_device *device)
> +{
> + struct igb *igb = to_igb_state(device);
> + u64 iova_tx, iova_rx;
> + u32 ctrl, rctl;
> + u16 cmd_reg;
> + int retries;
> +
> + VFIO_ASSERT_GE(device->driver.region.size, sizeof(struct igb));
> +
> + /* Set up rings and calculate IOVAs */
> + igb->bar0 = device->bars[0].vaddr;
> +
> + iova_tx = to_iova(device, igb->tx_ring);
> + iova_rx = to_iova(device, igb->rx_ring);
> +
> + igb_reset(igb);
[Severity: Medium]
Is it safe to perform MMIO accesses in igb_reset() before the PCI memory
space is enabled below?
If the device was recently reset or the system does not pre-enable memory
space, these early MMIO accesses might fail.
> +
> + /* Signal that the driver is loaded */
> + ctrl = igb_read32(igb, E1000_CTRL_EXT);
> + ctrl |= E1000_CTRL_EXT_DRV_LOAD;
> + ctrl &= ~E1000_CTRL_EXT_LINK_MODE_MASK;
> + igb_write32(igb, E1000_CTRL_EXT, ctrl);
> +
> + /* Enable PCI Bus Master. */
> + cmd_reg = vfio_pci_config_readw(device, PCI_COMMAND);
> + if ((cmd_reg & (PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY)) !=
> + (PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY)) {
> + cmd_reg |= (PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY);
> + vfio_pci_config_writew(device, PCI_COMMAND, cmd_reg);
> + }
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260714-igb_v3_b4-v5-0-91503eddb98b@google.com?part=1
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v5 2/5] vfio: selftests: igb: Use PHY internal loopback on 82576
2026-07-14 20:57 [PATCH v5 0/5] vfio: selftests: Add driver for Intel Ethernet Gigabit Controller (IGB) Josh Hilke
2026-07-14 20:57 ` [PATCH v5 1/5] vfio: selftests: igb: Add driver for Intel 82576 device Josh Hilke
@ 2026-07-14 20:57 ` Josh Hilke
2026-07-14 20:57 ` [PATCH v5 3/5] vfio: selftests: Add helpers to re-enable interrupts Josh Hilke
` (2 subsequent siblings)
4 siblings, 0 replies; 8+ messages in thread
From: Josh Hilke @ 2026-07-14 20:57 UTC (permalink / raw)
To: David Matlack, Alex Williamson
Cc: Shuah Khan, linux-kernel, kvm, linux-kselftest, Vipin Sharma,
Josh Hilke, Alex Williamson
From: Alex Williamson <alex.williamson@nvidia.com>
The submitted driver waits for PHY autonegotiation and then enables MAC
loopback via RCTL.LBM_MAC. QEMU's emulated igb tolerates this, but the
82576 datasheet rejects the MAC loopback path on real hardware:
Section 3.5.6.1 (Loopback Support / General): "Use PHY Loopback
instead of MAC Loopback on the 82576."
Section 3.5.6.2 (MAC Loopback): "MAC Loopback is not used on this
device."
Section 3.5.6.3.1 (Setting the 82576 to PHY loopback Mode): set PHY
control register bits 8 (duplex), 14 (loopback), clear bit 12
(autoneg enable), set the speed via bits 6 and 13. For 1Gb/s the
register value is 0x4140.
Section 8.10.1 (RCTL register): "When using the internal PHY, LBM
should remain set to 00b and the PHY instead configured for
loopback through the MDIO interface."
Replace igb_phy_setup_autoneg() with igb_setup_loopback() which:
- writes PHY register 0 with LOOPBACK | SPEED_1000 | FULL_DUPLEX
- forces the MAC into 1Gb/s full duplex via CTRL.FRCSPD, CTRL.FRCDPX,
CTRL.SPD_1000, CTRL.FD, CTRL.SLU; without forcing the MAC link
state, the descriptor engine does not run on real hardware
PHY internal loopback (section 3.5.6.3) wraps data at the end of the
PHY datapath before the MDI, so the physical link state and cable
speed are irrelevant. This matches the kernel ethtool selftest path
in igb_integrated_phy_loopback()
(drivers/net/ethernet/intel/igb/igb_ethtool.c).
QEMU's igb emulation drives STATUS.LU exclusively from its autoneg-done
timer or a network-backend link-state change; the guest cannot set
STATUS.LU through CTRL.SLU. Its receive path checks STATUS.LU
(e1000x_hw_rx_enabled in hw/net/e1000x_common.c) and drops every
loopback frame until LU is set. Issue a one-shot autoneg-restart PHY
write at the top of igb_setup_loopback() to kick the timer; the
subsequent PHY write clears autoneg-enable, so on real hardware
autoneg never starts and the write is a no-op.
QEMU's igb also does not honor PHY register 0 bit 14 (PHY internal
loopback) and relies on RCTL.LBM_MAC to wrap TX descriptors back to
the RX queue. Datasheet 8.10.1 advises that LBM remain 00b when
using the internal PHY, but empirically setting LBM_MAC has no
observable effect on real 82576 (MAC loopback is not implemented per
3.5.6.2), so set it alongside PHY loopback as the actual loopback
mechanism under QEMU. With these two QEMU-only accommodations the
selftest works in both environments without environment-specific code
paths.
Remove igb_read_phy() which becomes unused.
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
---
tools/testing/selftests/vfio/lib/drivers/igb/igb.c | 121 +++++++++++++--------
1 file changed, 73 insertions(+), 48 deletions(-)
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
index a59b95303092..2b444be4bdfe 100644
--- a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
@@ -115,57 +115,70 @@ static int igb_write_phy(struct igb *igb, u32 offset, u16 data)
return 0;
}
-static int igb_read_phy(struct igb *igb, u32 offset, u16 *data)
+/*
+ * Configure the device for PHY internal loopback per 82576 datasheet
+ * section 3.5.6.3.1. Force the PHY to 1Gb/s full duplex with loopback
+ * enabled, then force the MAC link state to match. Internal loopback
+ * wraps data at the end of the PHY datapath (section 3.5.6.3), so the
+ * physical link state is irrelevant.
+ *
+ * Section 3.5.6.1 directs to "Use PHY Loopback instead of MAC Loopback
+ * on the 82576", and section 3.5.6.2 states "MAC Loopback is not used
+ * on this device." RCTL.LBM_MAC is still set elsewhere as a QEMU-only
+ * accommodation; see the RCTL programming in the caller for the
+ * rationale.
+ */
+static void igb_setup_loopback(struct igb *igb)
{
- u32 mdic;
- int i;
-
- mdic = ((offset << E1000_MDIC_REG_SHIFT) |
- (1 << E1000_MDIC_PHY_SHIFT) |
- E1000_MDIC_OP_READ);
-
- igb_write32(igb, E1000_MDIC, mdic);
-
- for (i = 0; i < 1000; i++) {
- usleep(50);
- mdic = igb_read32(igb, E1000_MDIC);
- if (mdic & E1000_MDIC_READY)
- break;
- }
-
- if (!(mdic & E1000_MDIC_READY))
- return -1;
-
- if (mdic & E1000_MDIC_ERROR)
- return -1;
-
- *data = (u16)mdic;
- return 0;
-}
-
-static void igb_phy_setup_autoneg(struct igb *igb)
-{
- int timeout_ms = 1000;
- bool success = false;
- u16 phy_status;
+ u32 ctrl;
int ret;
- int i;
- /* Trigger auto-negotiation */
- ret = igb_write_phy(igb, MII_BMCR,
+ /*
+ * Kick the autoneg machinery solely to bring STATUS.LU up under
+ * QEMU's igb emulation: QEMU only updates STATUS.LU via its
+ * autoneg-done timer, and without LU set its receive path
+ * (e1000x_hw_rx_enabled) drops every loopback frame. On real
+ * hardware autoneg cannot complete before the next PHY write
+ * below clears the autoneg-enable bit, so this is effectively a
+ * no-op there.
+ */
+ (void)igb_write_phy(igb, MII_BMCR,
BMCR_ANENABLE | BMCR_ANRESTART);
+
+ /* PHY control: loopback + 1Gb/s full duplex, autoneg disabled. */
+ ret = igb_write_phy(igb, MII_BMCR,
+ BMCR_LOOPBACK |
+ BMCR_SPEED1000 |
+ BMCR_FULLDPLX);
VFIO_ASSERT_EQ(ret, 0, "Failed to write PHY control register");
- for (i = 0; i < timeout_ms; i++) {
- if (igb_read_phy(igb, MII_BMSR, &phy_status) == 0) {
- success = !!(phy_status & BMSR_ANEGCOMPLETE);
- if (success)
- break;
- }
- usleep(1000);
- }
+ /*
+ * Brief delay before forcing the MAC, mirroring the kernel ethtool
+ * selftest in igb_integrated_phy_loopback(). Not specified by the
+ * datasheet, but empirically required by the kernel driver.
+ */
+ usleep(50000);
+
+ /*
+ * Force the MAC to 1Gb/s full duplex with link up. Without forcing
+ * the link state the descriptor engine does not run, since the chip
+ * normally waits for a real negotiated link.
+ */
+ ctrl = igb_read32(igb, E1000_CTRL);
+ ctrl &= ~E1000_CTRL_SPD_SEL;
+ ctrl |= E1000_CTRL_FRCSPD |
+ E1000_CTRL_FRCDPX |
+ E1000_CTRL_SPD_1000 |
+ E1000_CTRL_FD |
+ E1000_CTRL_SLU;
+ igb_write32(igb, E1000_CTRL, ctrl);
- VFIO_ASSERT_TRUE(success, "Auto-negotiation did not complete in time");
+ /*
+ * Settling delay matching the kernel ethtool selftest's msleep(500)
+ * at the tail of igb_integrated_phy_loopback(). Not specified by
+ * the datasheet; empirical, and inherited from the kernel driver.
+ */
+ usleep(500000);
}
static int igb_probe(struct vfio_pci_device *device)
@@ -221,8 +234,8 @@ static void igb_init(struct vfio_pci_device *device)
vfio_pci_config_writew(device, PCI_COMMAND, cmd_reg);
}
- /* Trigger autonegotiation. This enables IGB to transmit data. */
- igb_phy_setup_autoneg(igb);
+ /* Configure PHY internal loopback for testing. */
+ igb_setup_loopback(igb);
/*
* Disable DMA re-send on PCIe completion timeout (82576 datasheet
@@ -277,12 +290,24 @@ static void igb_init(struct vfio_pci_device *device)
}
VFIO_ASSERT_GE(retries, 0);
- /* Enable Receiver and Transmitter */
+ /*
+ * Enable Receiver and Transmitter. RCTL.LBM_MAC is set in addition
+ * to PHY loopback as a QEMU-only accommodation: QEMU's emulated igb
+ * does not honor PHY register 0 bit 14 (PHY internal loopback) and
+ * relies on RCTL.LBM_MAC to wrap TX descriptors back to the RX
+ * queue. Datasheet 8.10.1 (RCTL register) advises "When using the
+ * internal PHY, LBM should remain set to 00b", so setting LBM_MAC
+ * here deviates from datasheet guidance; empirically the bit has
+ * no observable effect on real 82576 hardware because MAC loopback
+ * is not implemented (datasheet 3.5.6.2). Setting both lets the
+ * selftest work on both real hardware and QEMU without conditional
+ * code paths.
+ */
rctl = E1000_RCTL_EN | /* Receiver Enable */
E1000_RCTL_UPE | /* Unicast Promiscuous (for dummy MAC) */
E1000_RCTL_MPE | /* Multicast Promiscuous */
E1000_RCTL_BAM | /* Broadcast Accept Mode */
- E1000_RCTL_LBM_MAC | /* MAC Loopback Mode */
+ E1000_RCTL_LBM_MAC | /* MAC Loopback - for QEMU emulation only */
E1000_RCTL_SECRC; /* Strip CRC (needed for memcmp) */
igb_write32(igb, E1000_RCTL, rctl);
igb_write32(igb, E1000_TCTL, E1000_TCTL_EN);
--
2.55.0.141.g00534a21ce-goog
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 3/5] vfio: selftests: Add helpers to re-enable interrupts
2026-07-14 20:57 [PATCH v5 0/5] vfio: selftests: Add driver for Intel Ethernet Gigabit Controller (IGB) Josh Hilke
2026-07-14 20:57 ` [PATCH v5 1/5] vfio: selftests: igb: Add driver for Intel 82576 device Josh Hilke
2026-07-14 20:57 ` [PATCH v5 2/5] vfio: selftests: igb: Use PHY internal loopback on 82576 Josh Hilke
@ 2026-07-14 20:57 ` Josh Hilke
2026-07-14 20:57 ` [PATCH v5 4/5] vfio: selftests: igb: Factor hardware programming into igb_hw_init() Josh Hilke
2026-07-14 20:57 ` [PATCH v5 5/5] vfio: selftests: igb: Recover after DMA-read faults Josh Hilke
4 siblings, 0 replies; 8+ messages in thread
From: Josh Hilke @ 2026-07-14 20:57 UTC (permalink / raw)
To: David Matlack, Alex Williamson
Cc: Shuah Khan, linux-kernel, kvm, linux-kselftest, Vipin Sharma,
Josh Hilke, Alex Williamson
From: Alex Williamson <alex.williamson@nvidia.com>
Selftest drivers that recover from a fault by issuing VFIO_DEVICE_RESET
need to re-arm device interrupts afterwards. VFIO_DEVICE_RESET tears
down the kernel-side IRQ trigger so a subsequent VFIO_DEVICE_SET_IRQS
is required, but the user-side eventfds (and any fd cached in a test
fixture) are still valid and must be preserved.
vfio_pci_irq_enable() refuses to be called for vectors that already
have an eventfd (VFIO_ASSERT_LT), and vfio_pci_irq_disable() closes
all eventfds before resetting the trigger, so neither is suitable.
Add vfio_pci_irq_reenable(device, index, vector, count) which asserts
that the requested range has existing eventfds and re-issues
VFIO_DEVICE_SET_IRQS using them. Signature mirrors vfio_pci_irq_enable().
Add vfio_pci_msi{,x}_reenable() wrappers around vfio_pci_irq_reenable()
for additional ease of use and readability.
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
---
.../vfio/lib/include/libvfio/vfio_pci_device.h | 14 ++++++++++++++
tools/testing/selftests/vfio/lib/vfio_pci_device.c | 22 ++++++++++++++++++++++
2 files changed, 36 insertions(+)
diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
index 2858885a89bb..2e67afc0d580 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
@@ -68,6 +68,8 @@ void vfio_pci_config_access(struct vfio_pci_device *device, bool write,
void vfio_pci_irq_enable(struct vfio_pci_device *device, u32 index,
u32 vector, int count);
void vfio_pci_irq_disable(struct vfio_pci_device *device, u32 index);
+void vfio_pci_irq_reenable(struct vfio_pci_device *device, u32 index,
+ u32 vector, int count);
void vfio_pci_irq_trigger(struct vfio_pci_device *device, u32 index, u32 vector);
static inline void fcntl_set_nonblock(int fd)
@@ -92,6 +94,12 @@ static inline void vfio_pci_msi_disable(struct vfio_pci_device *device)
vfio_pci_irq_disable(device, VFIO_PCI_MSI_IRQ_INDEX);
}
+static inline void vfio_pci_msi_reenable(struct vfio_pci_device *device,
+ u32 vector, int count)
+{
+ vfio_pci_irq_reenable(device, VFIO_PCI_MSI_IRQ_INDEX, vector, count);
+}
+
static inline void vfio_pci_msix_enable(struct vfio_pci_device *device,
u32 vector, int count)
{
@@ -103,6 +111,12 @@ static inline void vfio_pci_msix_disable(struct vfio_pci_device *device)
vfio_pci_irq_disable(device, VFIO_PCI_MSIX_IRQ_INDEX);
}
+static inline void vfio_pci_msix_reenable(struct vfio_pci_device *device,
+ u32 vector, int count)
+{
+ vfio_pci_irq_reenable(device, VFIO_PCI_MSIX_IRQ_INDEX, vector, count);
+}
+
static inline int __to_iova(struct vfio_pci_device *device, void *vaddr, iova_t *iova)
{
return __iommu_hva2iova(device->iommu, vaddr, iova);
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index fc75e04ef010..7b8394d0ac50 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -106,6 +106,28 @@ void vfio_pci_irq_disable(struct vfio_pci_device *device, u32 index)
vfio_pci_irq_set(device, index, 0, 0, NULL);
}
+/*
+ * Re-issue VFIO_DEVICE_SET_IRQS for an already-enabled vector range using
+ * the existing eventfds. Intended for drivers that need to re-arm device
+ * interrupts after a VFIO_DEVICE_RESET, which tears down the kernel-side
+ * IRQ trigger but leaves user-side eventfds intact. Recreating the
+ * eventfds would invalidate any test-fixture cache of the fd, so this
+ * helper deliberately preserves them.
+ */
+void vfio_pci_irq_reenable(struct vfio_pci_device *device, u32 index,
+ u32 vector, int count)
+{
+ int i;
+
+ check_supported_irq_index(index);
+
+ for (i = vector; i < vector + count; i++)
+ VFIO_ASSERT_GE(device->msi_eventfds[i], 0,
+ "vector %d eventfd not allocated\n", i);
+
+ vfio_pci_irq_set(device, index, vector, count, device->msi_eventfds + vector);
+}
+
static void vfio_pci_irq_get(struct vfio_pci_device *device, u32 index,
struct vfio_irq_info *irq_info)
{
--
2.55.0.141.g00534a21ce-goog
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 4/5] vfio: selftests: igb: Factor hardware programming into igb_hw_init()
2026-07-14 20:57 [PATCH v5 0/5] vfio: selftests: Add driver for Intel Ethernet Gigabit Controller (IGB) Josh Hilke
` (2 preceding siblings ...)
2026-07-14 20:57 ` [PATCH v5 3/5] vfio: selftests: Add helpers to re-enable interrupts Josh Hilke
@ 2026-07-14 20:57 ` Josh Hilke
2026-07-14 20:57 ` [PATCH v5 5/5] vfio: selftests: igb: Recover after DMA-read faults Josh Hilke
4 siblings, 0 replies; 8+ messages in thread
From: Josh Hilke @ 2026-07-14 20:57 UTC (permalink / raw)
To: David Matlack, Alex Williamson
Cc: Shuah Khan, linux-kernel, kvm, linux-kselftest, Vipin Sharma,
Josh Hilke, Alex Williamson
From: Alex Williamson <alex.williamson@nvidia.com>
Split the device register programming out of igb_init() into a new
igb_hw_init() helper so that the same sequence can be re-run after a
VFIO_DEVICE_RESET to restore the registers that CTRL.RST clears. No
functional change for the initial path.
igb_init() now performs the one-shot setup: region size assertion, BAR
mapping, CTRL.RST + IMC mask-all to put the device into a known state,
and vfio_pci_msix_enable() to set up the kernel-side IRQ trigger.
igb_hw_init() does the rest: ring pointer setup and IOVA calc,
CTRL_EXT, PCI bus master, GCR, PHY loopback, descriptor rings, RCTL,
TCTL, GPIE/EIAC/EIAM/EIMS/IVAR, and driver-state initialization.
vfio_pci_msix_enable() moves from after RCTL/TCTL to before all
device-side programming. Its only side effects are the VFIO kernel
IRQ trigger setup and the PCI MSI-X capability bits in config space;
neither has any ordering dependency on the 82576 device register
writes performed in igb_hw_init(). Performing it once in igb_init()
keeps igb_hw_init() reusable from the reset recovery path (which uses
vfio_pci_irq_reenable() to re-arm the existing trigger).
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
Reviewed-by: David Matlack <dmatlack@google.com>
---
tools/testing/selftests/vfio/lib/drivers/igb/igb.c | 41 ++++++++++++++++------
1 file changed, 31 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
index 2b444be4bdfe..8eaf120330dc 100644
--- a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
@@ -202,7 +202,13 @@ static void igb_reset(struct igb *igb)
igb_write32(igb, E1000_IMC, 0xFFFFFFFF);
}
-static void igb_init(struct vfio_pci_device *device)
+/*
+ * Program the device into a usable state. Split out of igb_init() so it
+ * can be reused after a device reset to re-program the registers that
+ * CTRL.RST clears. Expects bar0 to be mapped and MSI-X already enabled
+ * via VFIO.
+ */
+static void igb_hw_init(struct vfio_pci_device *device)
{
struct igb *igb = to_igb_state(device);
u64 iova_tx, iova_rx;
@@ -210,15 +216,10 @@ static void igb_init(struct vfio_pci_device *device)
u16 cmd_reg;
int retries;
- VFIO_ASSERT_GE(device->driver.region.size, sizeof(struct igb));
-
- /* Set up rings and calculate IOVAs */
- igb->bar0 = device->bars[0].vaddr;
-
iova_tx = to_iova(device, igb->tx_ring);
iova_rx = to_iova(device, igb->rx_ring);
- igb_reset(igb);
+
/* Signal that the driver is loaded */
ctrl = igb_read32(igb, E1000_CTRL_EXT);
@@ -312,9 +313,6 @@ static void igb_init(struct vfio_pci_device *device)
igb_write32(igb, E1000_RCTL, rctl);
igb_write32(igb, E1000_TCTL, E1000_TCTL_EN);
- /* Enable MSI-X with 1 vector for the test */
- vfio_pci_msix_enable(device, MSIX_VECTOR, 1);
-
/*
* Program MSI-X interrupt routing per 82576 datasheet:
*
@@ -354,6 +352,29 @@ static void igb_init(struct vfio_pci_device *device)
device->driver.msi = MSIX_VECTOR;
}
+static void igb_init(struct vfio_pci_device *device)
+{
+ struct igb *igb = to_igb_state(device);
+
+ VFIO_ASSERT_GE(device->driver.region.size, sizeof(struct igb));
+
+ igb->bar0 = device->bars[0].vaddr;
+
+ igb_reset(igb);
+
+ /*
+ * Enable MSI-X via VFIO before device-side register programming.
+ * vfio_pci_msix_enable() only touches the VFIO IRQ machinery and the
+ * PCI MSI-X capability via config space; it has no ordering
+ * dependency on the device-side writes performed by igb_hw_init().
+ * Placing it here keeps igb_hw_init() reusable from the reset
+ * recovery path (which calls vfio_pci_irq_reenable() instead).
+ */
+ vfio_pci_msix_enable(device, MSIX_VECTOR, 1);
+
+ igb_hw_init(device);
+}
+
static void igb_remove(struct vfio_pci_device *device)
{
struct igb *igb = to_igb_state(device);
--
2.55.0.141.g00534a21ce-goog
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 5/5] vfio: selftests: igb: Recover after DMA-read faults
2026-07-14 20:57 [PATCH v5 0/5] vfio: selftests: Add driver for Intel Ethernet Gigabit Controller (IGB) Josh Hilke
` (3 preceding siblings ...)
2026-07-14 20:57 ` [PATCH v5 4/5] vfio: selftests: igb: Factor hardware programming into igb_hw_init() Josh Hilke
@ 2026-07-14 20:57 ` Josh Hilke
2026-07-14 21:12 ` sashiko-bot
4 siblings, 1 reply; 8+ messages in thread
From: Josh Hilke @ 2026-07-14 20:57 UTC (permalink / raw)
To: David Matlack, Alex Williamson
Cc: Shuah Khan, linux-kernel, kvm, linux-kselftest, Vipin Sharma,
Josh Hilke, Alex Williamson
From: Alex Williamson <alex.williamson@nvidia.com>
The mix_and_match test intentionally submits a TX descriptor with an
unmapped source IOVA so that the DMA read fails. On real 82576
hardware the resulting fault leaves the descriptor engine unable to
service subsequent valid descriptors, so the next memcpy in the same
test iteration times out.
The 82576 datasheet (section 4.2.1.6.1) describes CTRL.RST as the
software mechanism to recover from a hung device. Empirically
CTRL.RST alone is not sufficient in this state: the visible queue
registers are reinitialized, but the next valid memcpy still posts
descriptors without any TDH/TDT progress in the same process. A
fresh device open after the failure works, which points to a reset
scope broader than CTRL.RST being required. The 82576 advertises
PCIe FLR; VFIO_DEVICE_RESET drives FLR and supplies that scope while
preserving the selftest process and its DMA mappings.
Add igb_error_reset_and_reinit() implementing the recovery sequence:
issue VFIO_DEVICE_RESET, re-arm the kernel-side MSI-X trigger against
the still-valid eventfd via vfio_pci_irq_reenable() (this does not
touch the eventfd, which test fixtures may have cached), and
re-program the device via igb_hw_init(). FLR clears EICR and leaves
EIMS=0, so no explicit interrupt mask or cause writes are needed.
igb_hw_init() resets tx_tail/rx_tail to 0 and igb_memcpy_start() zeros
each descriptor before submission, so no ring memset is needed either.
Call this from igb_memcpy_wait() on completion timeout, preceded by a
10 ms delay so that PCIe/IOMMU/AER error handling triggered by the
just-observed DMA fault can release the device lock VFIO_DEVICE_RESET
contends for. The delay is heuristic and tied to the fault path, so
it lives at the call site rather than inside the reset helper. The
failed memcpy still returns -ETIMEDOUT; reset recovery only ensures
the next operation starts from a usable device state.
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
Reviewed-by: David Matlack <dmatlack@google.com>
---
tools/testing/selftests/vfio/lib/drivers/igb/igb.c | 45 +++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
index 8eaf120330dc..f50d450d3e94 100644
--- a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
+++ b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
@@ -458,6 +458,28 @@ static void igb_memcpy_start(struct vfio_pci_device *device, iova_t src,
igb_write32(igb, E1000_TDT(0), igb->tx_tail);
}
+/*
+ * Reset the device via VFIO_DEVICE_RESET (PCIe FLR on the 82576) and
+ * re-program it. VFIO_DEVICE_RESET tears down the kernel-side MSI-X
+ * trigger but leaves user-side eventfds intact, so re-arm the trigger
+ * via vfio_pci_irq_reenable() before reprogramming so any caller-cached
+ * eventfd remains valid.
+ *
+ * FLR clears device-side state to power-on reset values (datasheet
+ * 4.2.1.5.1: a PF FLR is "equivalent to a D0->D3->D0 transition"), so
+ * EIMS and EICR come back as 0 from their register-defined initial
+ * values, and igb_hw_init() resets tx_tail/rx_tail to 0. The next
+ * igb_memcpy_start() will memset each descriptor it touches before
+ * submission, so no explicit IMC/EICR writes or ring memsets are
+ * needed here.
+ */
+static void igb_error_reset_and_reinit(struct vfio_pci_device *device)
+{
+ vfio_pci_device_reset(device);
+ vfio_pci_msix_reenable(device, MSIX_VECTOR, 1);
+ igb_hw_init(device);
+}
+
static int igb_memcpy_wait(struct vfio_pci_device *device)
{
struct igb *igb = to_igb_state(device);
@@ -500,7 +522,28 @@ static int igb_memcpy_wait(struct vfio_pci_device *device)
igb_irq_enable(igb);
- return (status & 1) ? 0 : -ETIMEDOUT;
+ if (status & 1)
+ return 0;
+
+ /*
+ * The descriptor never completed. On real 82576 hardware this
+ * typically follows a DMA-read fault from one of the intentional
+ * unmapped-IOVA tests; the fault leaves the descriptor engine
+ * unable to service subsequent valid descriptors. CTRL.RST alone
+ * reinitializes the queue registers but leaves the engine wedged
+ * for the current process, so a broader VFIO_DEVICE_RESET (FLR)
+ * is required.
+ *
+ * Delay before requesting reset so PCIe/IOMMU/AER error handling
+ * triggered by the just-observed DMA fault can release the device
+ * lock VFIO_DEVICE_RESET contends for. The 10 ms value is
+ * heuristic. The current memcpy still fails with -ETIMEDOUT;
+ * recovery only ensures the next memcpy starts from a usable state.
+ */
+ usleep(10000);
+ igb_error_reset_and_reinit(device);
+
+ return -ETIMEDOUT;
}
static void igb_send_msi(struct vfio_pci_device *device)
--
2.55.0.141.g00534a21ce-goog
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH v5 5/5] vfio: selftests: igb: Recover after DMA-read faults
2026-07-14 20:57 ` [PATCH v5 5/5] vfio: selftests: igb: Recover after DMA-read faults Josh Hilke
@ 2026-07-14 21:12 ` sashiko-bot
0 siblings, 0 replies; 8+ messages in thread
From: sashiko-bot @ 2026-07-14 21:12 UTC (permalink / raw)
To: Josh Hilke; +Cc: kvm
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Test flakiness due to fixed heuristic delay instead of polling on EAGAIN during VFIO_DEVICE_RESET
--
--- Patch [5]: [PATCH v5 5/5] vfio: selftests: igb: Recover after DMA-read faults ---
commit a631c99ce1be37dbbdda0314b730b2c6bd947b50
Author: Alex Williamson <alex.williamson@nvidia.com>
vfio: selftests: igb: Recover after DMA-read faults
This commit adds recovery logic to the igb selftest when an intentional DMA
read fault causes the device to hang. It introduces a reset and re-init
sequence using VFIO_DEVICE_RESET, including a 10ms delay to allow kernel
error handlers to release the device lock.
> diff --git a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
> --- a/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
> +++ b/tools/testing/selftests/vfio/lib/drivers/igb/igb.c
[ ... ]
> @@ -500,7 +522,28 @@ static int igb_memcpy_wait(struct vfio_pci_device *device)
>
> igb_irq_enable(igb);
>
> - return (status & 1) ? 0 : -ETIMEDOUT;
> + if (status & 1)
> + return 0;
> +
> + /*
> + * The descriptor never completed. On real 82576 hardware this
> + * typically follows a DMA-read fault from one of the intentional
> + * unmapped-IOVA tests; the fault leaves the descriptor engine
> + * unable to service subsequent valid descriptors. CTRL.RST alone
> + * reinitializes the queue registers but leaves the engine wedged
> + * for the current process, so a broader VFIO_DEVICE_RESET (FLR)
> + * is required.
> + *
> + * Delay before requesting reset so PCIe/IOMMU/AER error handling
> + * triggered by the just-observed DMA fault can release the device
> + * lock VFIO_DEVICE_RESET contends for. The 10 ms value is
> + * heuristic. The current memcpy still fails with -ETIMEDOUT;
> + * recovery only ensures the next memcpy starts from a usable state.
> + */
> + usleep(10000);
> + igb_error_reset_and_reinit(device);
[Severity: Medium]
Will this fixed heuristic delay cause test flakiness under heavy load?
If the kernel's PCIe/IOMMU/AER error handling takes longer than 10ms to
complete (for example, when KASAN or other heavy debugging options are
enabled), the device lock might still be held.
Looking at the kernel side in drivers/vfio/pci/vfio_pci_core.c:
vfio_pci_ioctl_reset(), lock contention causes pci_try_reset_function() to
return -EAGAIN:
ret = pci_try_reset_function(vdev->pdev);
if (__vfio_pci_memory_enabled(vdev))
vfio_pci_dma_buf_move(vdev, false);
up_write(&vdev->memory_lock);
return ret;
Since igb_error_reset_and_reinit() calls vfio_pci_device_reset(), which
asserts that the ioctl returns 0, would this lock contention cause an
immediate test suite failure?
Should this code explicitly poll for -EAGAIN from the ioctl instead of
relying entirely on a fixed sleep?
> + return -ETIMEDOUT;
> }
>
> static void igb_send_msi(struct vfio_pci_device *device)
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260714-igb_v3_b4-v5-0-91503eddb98b@google.com?part=5
^ permalink raw reply [flat|nested] 8+ messages in thread