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Message-ID: <20250602230641.821485-2-wathsala.vithanage@arm.com>
Date: Mon, 2 Jun 2025 23:06:40 +0000
From: Wathsala Vithanage <wathsala.vithanage@....com>
To: linux-kernel@...r.kernel.org
Cc: alex.williamson@...hat.com,
gg@...pe.ca,
kevin.tian@...el.com,
bhelgaas@...gle.com,
pstanner@...hat.com,
linux@...blig.org,
schnelle@...ux.ibm.com,
Yunxiang.Li@....com,
kvm@...r.kernel.org,
Wathsala Vithanage <wathsala.vithanage@....com>
Subject: [RFC PATCH v2 1/1] vfio/pci: add PCIe TPH device ioctl
This patch introduces VFIO_DEVICE_PCI_TPH IOCTL to enable configuring of
TPH from the user space. It provides an interface to user space drivers
and VMMs to enable/disable TPH capability on PCIe devices and set
steering tags in MSI-X or steering-tag table entries or read steering
tags from the kernel to use them in device-specific mode.
Signed-off-by: Wathsala Vithanage <wathsala.vithanage@....com>
---
drivers/vfio/pci/vfio_pci_core.c | 153 +++++++++++++++++++++++++++++++
include/uapi/linux/vfio.h | 83 +++++++++++++++++
2 files changed, 236 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 6328c3a05bcd..efdc2f09aa75 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -29,6 +29,7 @@
#include <linux/nospec.h>
#include <linux/sched/mm.h>
#include <linux/iommufd.h>
+#include <linux/pci-tph.h>
#if IS_ENABLED(CONFIG_EEH)
#include <asm/eeh.h>
#endif
@@ -1444,6 +1445,156 @@ static int vfio_pci_ioctl_ioeventfd(struct vfio_pci_core_device *vdev,
ioeventfd.fd);
}
+static struct vfio_pci_tph_entry *vfio_pci_tph_get_ents(struct vfio_pci_tph *tph,
+ void __user *tph_ents,
+ size_t *ents_size)
+{
+ unsigned long minsz;
+ size_t size;
+
+ if (!ents_size)
+ return ERR_PTR(-EINVAL);
+
+ minsz = offsetofend(struct vfio_pci_tph, count);
+
+ size = tph->count * sizeof(struct vfio_pci_tph_entry);
+
+ if (tph->argsz - minsz < size)
+ return ERR_PTR(-EINVAL);
+
+ *ents_size = size;
+
+ return memdup_user(tph_ents, size);
+}
+
+static int vfio_pci_tph_set_st(struct vfio_pci_core_device *vdev,
+ struct vfio_pci_tph_entry *ents, int count)
+{
+ int i, err = 0;
+
+ for (i = 0; i < count && !err; i++)
+ err = pcie_tph_set_st_entry(vdev->pdev, ents[i].index,
+ ents[i].st);
+
+ return err;
+}
+
+static int vfio_pci_tph_get_st(struct vfio_pci_core_device *vdev,
+ struct vfio_pci_tph_entry *ents, int count)
+{
+ int i, mtype, err = 0;
+ u32 cpu_uid;
+
+ for (i = 0; i < count && !err; i++) {
+ if (ents[i].cpu_id >= nr_cpu_ids || !cpu_present(ents[i].cpu_id)) {
+ err = -EINVAL;
+ break;
+ }
+
+ cpu_uid = topology_core_id(ents[i].cpu_id);
+ mtype = (ents[i].flags & VFIO_TPH_MEM_TYPE_MASK) >>
+ VFIO_TPH_MEM_TYPE_SHIFT;
+
+ /*
+ * ph_ignore is always set.
+ * TPH implementation of the PCI subsystem forces processing
+ * hint to bi-directional by setting PH bits to 0 when
+ * acquiring Steering Tags from the platform firmware. It also
+ * discards the ph_ignore bit returned by firmware.
+ */
+ ents[i].ph_ignore = 1;
+
+ err = pcie_tph_get_cpu_st(vdev->pdev, mtype, cpu_uid,
+ &ents[i].st);
+ }
+
+ return err;
+}
+
+static int vfio_pci_tph_st_op(struct vfio_pci_core_device *vdev,
+ struct vfio_pci_tph *tph, void __user *tph_ents)
+{
+ int err = 0;
+ struct vfio_pci_tph_entry *ents;
+ size_t ents_size;
+
+ if (!tph->count || tph->count > VFIO_TPH_INFO_MAX) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ ents = vfio_pci_tph_get_ents(tph, tph_ents, &ents_size);
+ if (IS_ERR(ents)) {
+ err = PTR_ERR(ents);
+ goto out;
+ }
+
+ err = vfio_pci_tph_get_st(vdev, ents, tph->count);
+ if (err)
+ goto out_free_ents;
+
+ /*
+ * Set Steering tags. TPH will be disabled on the device by the PCI
+ * subsystem if there is an error.
+ */
+ if (tph->flags & VFIO_DEVICE_TPH_SET_ST) {
+ err = vfio_pci_tph_set_st(vdev, ents, tph->count);
+ if (err)
+ goto out_free_ents;
+ }
+
+ if (copy_to_user(tph_ents, ents, ents_size))
+ err = -EFAULT;
+
+out_free_ents:
+ kfree(ents);
+out:
+ return err;
+}
+
+static int vfio_pci_tph_enable(struct vfio_pci_core_device *vdev,
+ struct vfio_pci_tph *arg)
+{
+ return pcie_enable_tph(vdev->pdev, arg->flags & VFIO_TPH_ST_MODE_MASK);
+}
+
+static int vfio_pci_tph_disable(struct vfio_pci_core_device *vdev)
+{
+ pcie_disable_tph(vdev->pdev);
+ return 0;
+}
+
+static int vfio_pci_ioctl_tph(struct vfio_pci_core_device *vdev,
+ void __user *uarg)
+{
+ u32 op;
+ struct vfio_pci_tph tph;
+ size_t minsz = offsetofend(struct vfio_pci_tph, count);
+
+ if (copy_from_user(&tph, uarg, minsz))
+ return -EFAULT;
+
+ if (tph.argsz < minsz)
+ return -EINVAL;
+
+ op = tph.flags & VFIO_DEVICE_TPH_OP_MASK;
+
+ switch (op) {
+ case VFIO_DEVICE_TPH_ENABLE:
+ return vfio_pci_tph_enable(vdev, &tph);
+
+ case VFIO_DEVICE_TPH_DISABLE:
+ return vfio_pci_tph_disable(vdev);
+
+ case VFIO_DEVICE_TPH_GET_ST:
+ case VFIO_DEVICE_TPH_SET_ST:
+ return vfio_pci_tph_st_op(vdev, &tph, (u8 *)(uarg) + minsz);
+
+ default:
+ return -EINVAL;
+ }
+}
+
long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
unsigned long arg)
{
@@ -1468,6 +1619,8 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
return vfio_pci_ioctl_reset(vdev, uarg);
case VFIO_DEVICE_SET_IRQS:
return vfio_pci_ioctl_set_irqs(vdev, uarg);
+ case VFIO_DEVICE_PCI_TPH:
+ return vfio_pci_ioctl_tph(vdev, uarg);
default:
return -ENOTTY;
}
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 5764f315137f..1a56abdf9deb 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -873,6 +873,88 @@ struct vfio_device_ioeventfd {
#define VFIO_DEVICE_IOEVENTFD _IO(VFIO_TYPE, VFIO_BASE + 16)
+/**
+ * VFIO_DEVICE_PCI_TPH - _IO(VFIO_TYPE, VFIO_BASE + 22)
+ *
+ * This command is used to control PCIe TLP Processing Hints (TPH)
+ * capability in a PCIe device.
+ * It supports following operations on a PCIe device with respect to TPH
+ * capability.
+ *
+ * - Enabling/disabling TPH capability in a PCIe device.
+ *
+ * Setting VFIO_DEVICE_TPH_ENABLE flag enables TPH in no-steering-tag,
+ * interrupt-vector, or device-specific mode defined in the PCIe specficiation
+ * when feature flags TPH_ST_NS_MODE, TPH_ST_IV_MODE, and TPH_ST_DS_MODE are
+ * set respectively. TPH_ST_xx_MODE macros are defined in
+ * uapi/linux/pci_regs.h.
+ *
+ * VFIO_DEVICE_TPH_DISABLE disables PCIe TPH on the device.
+ *
+ * - Writing STs to MSI-X or ST table in a PCIe device.
+ *
+ * VFIO_DEVICE_TPH_SET_ST flag set steering tags on a device at an index in
+ * MSI-X or ST-table depending on the VFIO_TPH_ST_x_MODE flag used and
+ * returns the programmed steering tag values. The caller can set one or more
+ * steering tags by passing an array of vfio_pci_tph_entry objects containing
+ * cpu_id, cache_level, and MSI-X/ST-table index. The caller can also set the
+ * intended memory type and the processing hint by setting VFIO_TPH_MEM_TYPE_x
+ * and VFIO_TPH_HINT_x flags, respectively.
+ *
+ * - Reading Steering Tags (ST) from the host platform.
+ *
+ * VFIO_DEVICE_TPH_GET_ST flags returns steering tags to the caller. Caller
+ * can request one or more steering tags by passing an array of
+ * vfio_pci_tph_entry objects. Steering Tag for each request is returned via
+ * the st field in vfio_pci_tph_entry.
+ */
+struct vfio_pci_tph_entry {
+ /* in */
+ __u32 cpu_id; /* CPU logical ID */
+ __u32 cache_level; /* Cache level. L1 D= 0, L2D = 2, ...*/
+ __u8 flags;
+#define VFIO_TPH_MEM_TYPE_MASK 0x1
+#define VFIO_TPH_MEM_TYPE_SHIFT 0
+#define VFIO_TPH_MEM_TYPE_VMEM 0 /* Request volatile memory ST */
+#define VFIO_TPH_MEM_TYPE_PMEM 1 /* Request persistent memory ST */
+
+#define VFIO_TPH_HINT_MASK 0x3
+#define VFIO_TPH_HINT_SHIFT 1
+#define VFIO_TPH_HINT_BIDIR 0
+#define VFIO_TPH_HINT_REQSTR (1 << VFIO_TPH_HINT_SHIFT)
+#define VFIO_TPH_HINT_TARGET (2 << VFIO_TPH_HINT_SHIFT)
+#define VFIO_TPH_HINT_TARGET_PRIO (3 << VFIO_TPH_HINT_SHIFT)
+ __u8 pad0;
+ __u16 index; /* MSI-X/ST-table index to set ST */
+ /* out */
+ __u16 st; /* Steering-Tag */
+ __u8 ph_ignore; /* Platform ignored the Processing */
+ __u8 pad1;
+};
+
+struct vfio_pci_tph {
+ __u32 argsz; /* Size of vfio_pci_tph and info[] */
+ __u32 flags;
+#define VFIO_TPH_ST_MODE_MASK 0x7
+
+#define VFIO_DEVICE_TPH_OP_SHIFT 3
+#define VFIO_DEVICE_TPH_OP_MASK (0x7 << VFIO_DEVICE_TPH_OP_SHIFT)
+/* Enable TPH on device */
+#define VFIO_DEVICE_TPH_ENABLE 0
+/* Disable TPH on device */
+#define VFIO_DEVICE_TPH_DISABLE (1 << VFIO_DEVICE_TPH_OP_SHIFT)
+/* Get steering-tags */
+#define VFIO_DEVICE_TPH_GET_ST (2 << VFIO_DEVICE_TPH_OP_SHIFT)
+/* Set steering-tags */
+#define VFIO_DEVICE_TPH_SET_ST (4 << VFIO_DEVICE_TPH_OP_SHIFT)
+ __u32 count; /* Number of entries in ents[] */
+ struct vfio_pci_tph_entry ents[];
+#define VFIO_TPH_INFO_MAX 2048 /* Max entries in ents[] */
+};
+
+#define VFIO_DEVICE_PCI_TPH _IO(VFIO_TYPE, VFIO_BASE + 22)
+
+
/**
* VFIO_DEVICE_FEATURE - _IOWR(VFIO_TYPE, VFIO_BASE + 17,
* struct vfio_device_feature)
@@ -1468,6 +1550,7 @@ struct vfio_device_feature_bus_master {
};
#define VFIO_DEVICE_FEATURE_BUS_MASTER 10
+
/* -------- API for Type1 VFIO IOMMU -------- */
/**
--
2.43.0
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