On Mon, Oct 02, 2023 at 08:05:10PM +0800, Sui Jingfeng wrote:
Currently, the vga_is_firmware_default() function only works on x86 and
ia64, it is a no-op on the rest of the architectures. This patch completes
the implementation for it, the added code tries to capture the PCI (e) VGA
device that owns the firmware framebuffer, since only one GPU could own
the firmware fb, things are almost done once we have determined the boot
VGA device. As the PCI resource relocation do have a influence on the
results of identification, we make it available on architectures where PCI
resource relocation does happen at first. Because this patch is more
important for those architectures(such as arm, arm64, loongarch, mips and
risc-v etc).
There's a little too much going on this this patch. The problem is
very simple: currently we compare firmware BAR assignments with BARs
that may have been reassigned by Linux.
What if we did something like the patch below? I think it will be
less confusing if we only have one copy of the code related to
screen_info.
Bjorn
Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
---
drivers/pci/vgaarb.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 76 insertions(+)
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index 5e6b1eb54c64..02821c0f4cd0 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -60,6 +60,9 @@ static bool vga_arbiter_used;
static DEFINE_SPINLOCK(vga_lock);
static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
+/* The PCI(e) VGA device which owns the firmware framebuffer */
+static struct pci_dev *pdev_boot_vga;
+
static const char *vga_iostate_to_str(unsigned int iostate)
{
/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
@@ -582,6 +585,9 @@ static bool vga_is_firmware_default(struct pci_dev *pdev)
return true;
}
+#else
+ if (pdev_boot_vga && pdev_boot_vga == pdev)
+ return true;
#endif
return false;
}
@@ -1557,3 +1563,73 @@ static int __init vga_arb_device_init(void)
return rc;
}
subsys_initcall_sync(vga_arb_device_init);
+
+/*
+ * Get the physical address range that the firmware framebuffer occupies.
+ *
+ * Note that the global screen_info is arch-specific, thus CONFIG_SYSFB is
+ * chosen as compile-time conditional to suppress linkage problems on non-x86
+ * architectures.
+ *
+ * Returns true on success, otherwise return false.
+ */
+static bool vga_arb_get_firmware_fb_range(u64 *start, u64 *end)
+{
+ u64 fb_start = 0;
+ u64 fb_size = 0;
+ u64 fb_end;
+
+#if defined(CONFIG_X86) || defined(CONFIG_IA64) || defined(CONFIG_SYSFB)
+ fb_start = screen_info.lfb_base;
+ if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
+ fb_start |= (u64)screen_info.ext_lfb_base << 32;
+
+ fb_size = screen_info.lfb_size;
+#endif
+
+ /* No firmware framebuffer support */
+ if (!fb_start || !fb_size)
+ return false;
+
+ fb_end = fb_start + fb_size - 1;
+
+ *start = fb_start;
+ *end = fb_end;
+
+ return true;
+}
+
+/*
+ * Identify the PCI VGA device that contains the firmware framebuffer
+ */
+static void pci_boot_vga_capturer(struct pci_dev *pdev)
+{
+ u64 fb_start, fb_end;
+ struct resource *res;
+ unsigned int i;
+
+ if (pdev_boot_vga)
+ return;
+
+ if (!vga_arb_get_firmware_fb_range(&fb_start, &fb_end))
+ return;
+
+ pci_dev_for_each_resource(pdev, res, i) {
+ if (resource_type(res) != IORESOURCE_MEM)
+ continue;
+
+ if (!res->start || !res->end)
+ continue;
+
+ if (res->start <= fb_start && fb_end <= res->end) {
+ pdev_boot_vga = pdev;
+
+ vgaarb_info(&pdev->dev,
+ "BAR %u: %pR contains firmware FB [0x%llx-0x%llx]\n",
+ i, res, fb_start, fb_end);
+ break;
+ }
+ }
+}
+DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_CLASS_DISPLAY_VGA,
+ 8, pci_boot_vga_capturer);
PCI/VGA: Match firmware framebuffer before BAR reassignment
vga_is_firmware_default() decides a device is the firmware default VGA
device if it has a BAR that contains the framebuffer described by
screen_info.
Previously this was unreliable because the screen_info framebuffer address
comes from firmware, and the Linux PCI core may reassign device BARs before
vga_is_firmware_default() runs. This reassignment means the BAR may not
match the screen_info values, but we still want to select the device as the
firmware default.
Make vga_is_firmware_default() more reliable by running it as a quirk so it
happens before any BAR reassignment.
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index 5e6b1eb54c64..4a53e76caddd 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -60,6 +60,8 @@ static bool vga_arbiter_used;
static DEFINE_SPINLOCK(vga_lock);
static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
+static struct pci_dev *vga_firmware_device;
+
static const char *vga_iostate_to_str(unsigned int iostate)
{
/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
@@ -560,6 +562,7 @@ static bool vga_is_firmware_default(struct pci_dev *pdev)
u64 base = screen_info.lfb_base;
u64 size = screen_info.lfb_size;
struct resource *r;
+ unsigned int i;
u64 limit;
/* Select the device owning the boot framebuffer if there is one */
@@ -570,7 +573,7 @@ static bool vga_is_firmware_default(struct pci_dev *pdev)
limit = base + size;
/* Does firmware framebuffer belong to us? */
- pci_dev_for_each_resource(pdev, r) {
+ pci_dev_for_each_resource(pdev, r, i) {
if (resource_type(r) != IORESOURCE_MEM)
continue;
@@ -580,6 +583,8 @@ static bool vga_is_firmware_default(struct pci_dev *pdev)
if (base < r->start || limit >= r->end)
continue;
+ vgaarb_info(&pdev->dev, "BAR %u: %pR contains firmware framebuffer [%#010llx-%#010llx]\n",
+ i, r, base, limit - 1);
return true;
}
#endif
@@ -623,7 +628,7 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
if (boot_vga && boot_vga->is_firmware_default)
return false;
- if (vga_is_firmware_default(pdev)) {
+ if (pdev == vga_firmware_device) {
vgadev->is_firmware_default = true;
return true;
}
@@ -1557,3 +1562,14 @@ static int __init vga_arb_device_init(void)
return rc;
}
subsys_initcall_sync(vga_arb_device_init);
+
+static void vga_match_firmware_framebuffer(struct pci_dev *pdev)
+{
+ if (vga_firmware_device)
+ return;
+
+ if (vga_is_firmware_default(pdev))
+ vga_firmware_device = pdev;
+}
+DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_CLASS_DISPLAY_VGA,
+ 8, vga_match_firmware_framebuffer);
