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* [PATCH] vfio/pci: Add support for PCIe extended capabilities
@ 2021-08-10  6:25 Vivek Gautam
  2021-08-31 14:54 ` Will Deacon
                   ` (2 more replies)
  0 siblings, 3 replies; 15+ messages in thread
From: Vivek Gautam @ 2021-08-10  6:25 UTC (permalink / raw)
  To: will, julien.thierry.kdev, kvm
  Cc: andre.przywara, alexandru.elisei, lorenzo.pieralisi,
	jean-philippe, eric.auger, Vivek Gautam

Add support to parse extended configuration space for vfio based
assigned PCIe devices and add extended capabilities for the device
in the guest. This allows the guest to see and work on extended
capabilities, for example to toggle PRI extended cap to enable and
disable Shared virtual addressing (SVA) support.
PCIe extended capability header that is the first DWORD of all
extended caps is shown below -

   31               20  19   16  15                 0
   ____________________|_______|_____________________
  |    Next cap off    |  1h   |     Cap ID          |
  |____________________|_______|_____________________|

Out of the two upper bytes of extended cap header, the
lower nibble is actually cap version - 0x1.
'next cap offset' if present at bits [31:20], should be
right shifted by 4 bits to calculate the position of next
capability.
This change supports parsing and adding ATS, PRI and PASID caps.

Signed-off-by: Vivek Gautam <vivek.gautam@arm.com>
---
 include/kvm/pci.h |   6 +++
 vfio/pci.c        | 104 ++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 103 insertions(+), 7 deletions(-)

diff --git a/include/kvm/pci.h b/include/kvm/pci.h
index 0f2d5bb..a365337 100644
--- a/include/kvm/pci.h
+++ b/include/kvm/pci.h
@@ -165,6 +165,12 @@ struct pci_exp_cap {
 	u32 root_status;
 };
 
+struct pci_ext_cap_hdr {
+	u16	type;
+	/* bit 19:16 = 0x1: Cap version */
+	u16	next;
+};
+
 struct pci_device_header;
 
 typedef int (*bar_activate_fn_t)(struct kvm *kvm,
diff --git a/vfio/pci.c b/vfio/pci.c
index ea33fd6..d045e0d 100644
--- a/vfio/pci.c
+++ b/vfio/pci.c
@@ -665,19 +665,105 @@ static int vfio_pci_add_cap(struct vfio_device *vdev, u8 *virt_hdr,
 	return 0;
 }
 
+static ssize_t vfio_pci_ext_cap_size(struct pci_ext_cap_hdr *cap_hdr)
+{
+	switch (cap_hdr->type) {
+	case PCI_EXT_CAP_ID_ATS:
+		return PCI_EXT_CAP_ATS_SIZEOF;
+	case PCI_EXT_CAP_ID_PRI:
+		return PCI_EXT_CAP_PRI_SIZEOF;
+	case PCI_EXT_CAP_ID_PASID:
+		return PCI_EXT_CAP_PASID_SIZEOF;
+	default:
+		pr_err("unknown extended PCI capability 0x%x", cap_hdr->type);
+		return 0;
+	}
+}
+
+static int vfio_pci_add_ext_cap(struct vfio_device *vdev, u8 *virt_hdr,
+			    struct pci_ext_cap_hdr *cap, off_t pos)
+{
+	struct pci_ext_cap_hdr *last;
+
+	cap->next = 0;
+	last = PCI_CAP(virt_hdr, 0x100);
+
+	while (last->next)
+		last = PCI_CAP(virt_hdr, last->next);
+
+	last->next = pos;
+	/*
+	 * Out of the two upper bytes of extended cap header, the
+	 * nibble [19:16] is actually cap version that should be 0x1,
+	 * so shift back the actual 'next' value by 4 bits.
+	 */
+	last->next = (last->next << 4) | 0x1;
+	memcpy(virt_hdr + pos, cap, vfio_pci_ext_cap_size(cap));
+
+	return 0;
+
+}
+
+static int vfio_pci_parse_ext_caps(struct vfio_device *vdev, u8 *virt_hdr)
+{
+	int ret;
+	u16 pos, next;
+	struct pci_ext_cap_hdr *ext_cap;
+	struct vfio_pci_device *pdev = &vdev->pci;
+
+	/* Extended cap only for PCIe devices */
+	if (!arch_has_pci_exp())
+		return 0;
+
+	/* Extended caps start from 0x100 offset. */
+	pos = 0x100;
+
+	for (; pos; pos = next) {
+		ext_cap = PCI_CAP(&pdev->hdr, pos);
+		/*
+		 * Out of the two upper bytes of extended cap header, the
+		 * lowest nibble is actually cap version.
+		 * 'next cap offset' if present at bits [31:20], while
+		 * bits [19:16] are set to 1 to indicate cap version.
+		 * So to get position of next cap right shift by 4 bits.
+		 */
+		next = (ext_cap->next >> 4);
+
+		switch (ext_cap->type) {
+		case PCI_EXT_CAP_ID_ATS:
+			ret = vfio_pci_add_ext_cap(vdev, virt_hdr, ext_cap, pos);
+			if (ret)
+				return ret;
+			break;
+		case PCI_EXT_CAP_ID_PRI:
+			ret = vfio_pci_add_ext_cap(vdev, virt_hdr, ext_cap, pos);
+			if (ret)
+				return ret;
+			break;
+		case PCI_EXT_CAP_ID_PASID:
+			ret = vfio_pci_add_ext_cap(vdev, virt_hdr, ext_cap, pos);
+			if (ret)
+				return ret;
+			break;
+		}
+	}
+
+	return 0;
+}
+
 static int vfio_pci_parse_caps(struct vfio_device *vdev)
 {
 	int ret;
 	size_t size;
 	u16 pos, next;
 	struct pci_cap_hdr *cap;
-	u8 virt_hdr[PCI_DEV_CFG_SIZE_LEGACY];
+	u8 virt_hdr[PCI_DEV_CFG_SIZE];
 	struct vfio_pci_device *pdev = &vdev->pci;
 
 	if (!(pdev->hdr.status & PCI_STATUS_CAP_LIST))
 		return 0;
 
-	memset(virt_hdr, 0, PCI_DEV_CFG_SIZE_LEGACY);
+	memset(virt_hdr, 0, PCI_DEV_CFG_SIZE);
 
 	pos = pdev->hdr.capabilities & ~3;
 
@@ -715,9 +801,13 @@ static int vfio_pci_parse_caps(struct vfio_device *vdev)
 		}
 	}
 
+	ret = vfio_pci_parse_ext_caps(vdev, virt_hdr);
+	if (ret)
+		return ret;
+
 	/* Wipe remaining capabilities */
 	pos = PCI_STD_HEADER_SIZEOF;
-	size = PCI_DEV_CFG_SIZE_LEGACY - PCI_STD_HEADER_SIZEOF;
+	size = PCI_DEV_CFG_SIZE - PCI_STD_HEADER_SIZEOF;
 	memcpy((void *)&pdev->hdr + pos, virt_hdr + pos, size);
 
 	return 0;
@@ -725,7 +815,7 @@ static int vfio_pci_parse_caps(struct vfio_device *vdev)
 
 static int vfio_pci_parse_cfg_space(struct vfio_device *vdev)
 {
-	ssize_t sz = PCI_DEV_CFG_SIZE_LEGACY;
+	ssize_t sz = PCI_DEV_CFG_SIZE;
 	struct vfio_region_info *info;
 	struct vfio_pci_device *pdev = &vdev->pci;
 
@@ -831,10 +921,10 @@ static int vfio_pci_fixup_cfg_space(struct vfio_device *vdev)
 	/* Install our fake Configuration Space */
 	info = &vdev->regions[VFIO_PCI_CONFIG_REGION_INDEX].info;
 	/*
-	 * We don't touch the extended configuration space, let's be cautious
-	 * and not overwrite it all with zeros, or bad things might happen.
+	 * Update the extended configuration space as well since we
+	 * are now populating the extended capabilities.
 	 */
-	hdr_sz = PCI_DEV_CFG_SIZE_LEGACY;
+	hdr_sz = PCI_DEV_CFG_SIZE;
 	if (pwrite(vdev->fd, &pdev->hdr, hdr_sz, info->offset) != hdr_sz) {
 		vfio_dev_err(vdev, "failed to write %zd bytes to Config Space",
 			     hdr_sz);
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2021-10-04  9:47 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-10  6:25 [PATCH] vfio/pci: Add support for PCIe extended capabilities Vivek Gautam
2021-08-31 14:54 ` Will Deacon
2021-09-01 10:27   ` Andre Przywara
2021-09-01 10:44     ` Will Deacon
2021-09-02 10:28       ` Vivek Kumar Gautam
2021-08-31 17:14 ` Andre Przywara
2021-09-02 10:42   ` Vivek Kumar Gautam
2021-09-02  9:59 ` Alexandru Elisei
2021-09-02 10:48   ` Vivek Kumar Gautam
2021-09-03 15:15     ` Alexandru Elisei
2021-09-08  9:32       ` Vivek Kumar Gautam
2021-09-08  9:36         ` Vivek Kumar Gautam
2021-09-08 16:20           ` Alexandru Elisei
2021-09-08 16:18         ` Alexandru Elisei
2021-10-04  9:47         ` Will Deacon

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