[v2] drm/qxl: get vga ioports

Submitted by Gerd Hoffmann on Aug. 5, 2019, 10:54 a.m.

Details

Message ID 20190805105401.29874-1-kraxel@redhat.com
State Accepted
Commit fbf0a7f44cdd4041b5a3e2b14deaa0adebaf40da
Headers show
Series "drm/qxl: get vga ioports" ( rev: 2 ) in Spice

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Commit Message

Gerd Hoffmann Aug. 5, 2019, 10:54 a.m.
qxl has two modes: "native" (used by the drm driver) and "vga" (vga
compatibility mode, typically used for boot display and firmware
framebuffers).

Accessing any vga ioport will switch the qxl device into vga mode.
The qxl driver never does that, but other drivers accessing vga ports
can trigger that too and therefore disturb qxl operation.  So aquire
the legacy vga ioports from vgaarb to avoid that.

Reproducer: Boot kvm guest with both qxl and i915 vgpu, with qxl being
first in pci scan order.

v2: Skip this for secondary qxl cards which don't have vga mode in the
    first place (Frediano).

Cc: Frediano Ziglio <fziglio@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/gpu/drm/qxl/qxl_drv.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
index b57a37543613..fcb48ac60598 100644
--- a/drivers/gpu/drm/qxl/qxl_drv.c
+++ b/drivers/gpu/drm/qxl/qxl_drv.c
@@ -63,6 +63,11 @@  module_param_named(num_heads, qxl_num_crtc, int, 0400);
 static struct drm_driver qxl_driver;
 static struct pci_driver qxl_pci_driver;
 
+static bool is_vga(struct pci_dev *pdev)
+{
+	return pdev->class == PCI_CLASS_DISPLAY_VGA << 8;
+}
+
 static int
 qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
@@ -87,9 +92,17 @@  qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (ret)
 		goto disable_pci;
 
+	if (is_vga(pdev)) {
+		ret = vga_get_interruptible(pdev, VGA_RSRC_LEGACY_IO);
+		if (ret) {
+			DRM_ERROR("can't get legacy vga ioports\n");
+			goto disable_pci;
+		}
+	}
+
 	ret = qxl_device_init(qdev, &qxl_driver, pdev);
 	if (ret)
-		goto disable_pci;
+		goto put_vga;
 
 	ret = qxl_modeset_init(qdev);
 	if (ret)
@@ -109,6 +122,9 @@  qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	qxl_modeset_fini(qdev);
 unload:
 	qxl_device_fini(qdev);
+put_vga:
+	if (is_vga(pdev))
+		vga_put(pdev, VGA_RSRC_LEGACY_IO);
 disable_pci:
 	pci_disable_device(pdev);
 free_dev:
@@ -126,6 +142,8 @@  qxl_pci_remove(struct pci_dev *pdev)
 
 	qxl_modeset_fini(qdev);
 	qxl_device_fini(qdev);
+	if (is_vga(pdev))
+		vga_put(pdev, VGA_RSRC_LEGACY_IO);
 
 	dev->dev_private = NULL;
 	kfree(qdev);

Comments

> 
> qxl has two modes: "native" (used by the drm driver) and "vga" (vga
> compatibility mode, typically used for boot display and firmware
> framebuffers).
> 
> Accessing any vga ioport will switch the qxl device into vga mode.
> The qxl driver never does that, but other drivers accessing vga ports
> can trigger that too and therefore disturb qxl operation.  So aquire
> the legacy vga ioports from vgaarb to avoid that.
> 
> Reproducer: Boot kvm guest with both qxl and i915 vgpu, with qxl being
> first in pci scan order.
> 
> v2: Skip this for secondary qxl cards which don't have vga mode in the
>     first place (Frediano).
> 
> Cc: Frediano Ziglio <fziglio@redhat.com>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Acked-by: Frediano Ziglio <fziglio@redhat.com>

> ---
>  drivers/gpu/drm/qxl/qxl_drv.c | 20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> index b57a37543613..fcb48ac60598 100644
> --- a/drivers/gpu/drm/qxl/qxl_drv.c
> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> @@ -63,6 +63,11 @@ module_param_named(num_heads, qxl_num_crtc, int, 0400);
>  static struct drm_driver qxl_driver;
>  static struct pci_driver qxl_pci_driver;
>  
> +static bool is_vga(struct pci_dev *pdev)
> +{
> +	return pdev->class == PCI_CLASS_DISPLAY_VGA << 8;
> +}
> +
>  static int
>  qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  {
> @@ -87,9 +92,17 @@ qxl_pci_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
>  	if (ret)
>  		goto disable_pci;
>  
> +	if (is_vga(pdev)) {
> +		ret = vga_get_interruptible(pdev, VGA_RSRC_LEGACY_IO);
> +		if (ret) {
> +			DRM_ERROR("can't get legacy vga ioports\n");
> +			goto disable_pci;
> +		}
> +	}
> +
>  	ret = qxl_device_init(qdev, &qxl_driver, pdev);
>  	if (ret)
> -		goto disable_pci;
> +		goto put_vga;
>  
>  	ret = qxl_modeset_init(qdev);
>  	if (ret)
> @@ -109,6 +122,9 @@ qxl_pci_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
>  	qxl_modeset_fini(qdev);
>  unload:
>  	qxl_device_fini(qdev);
> +put_vga:
> +	if (is_vga(pdev))
> +		vga_put(pdev, VGA_RSRC_LEGACY_IO);
>  disable_pci:
>  	pci_disable_device(pdev);
>  free_dev:
> @@ -126,6 +142,8 @@ qxl_pci_remove(struct pci_dev *pdev)
>  
>  	qxl_modeset_fini(qdev);
>  	qxl_device_fini(qdev);
> +	if (is_vga(pdev))
> +		vga_put(pdev, VGA_RSRC_LEGACY_IO);
>  
>  	dev->dev_private = NULL;
>  	kfree(qdev);

Frediano