linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH v2] drm/qxl: get vga ioports
@ 2019-08-05 10:54 Gerd Hoffmann
  2019-09-11 15:40 ` Frediano Ziglio
  0 siblings, 1 reply; 2+ messages in thread
From: Gerd Hoffmann @ 2019-08-05 10:54 UTC (permalink / raw)
  To: dri-devel
  Cc: Gerd Hoffmann, Frediano Ziglio, Dave Airlie, David Airlie,
	Daniel Vetter, open list:DRM DRIVER FOR QXL VIRTUAL GPU,
	open list:DRM DRIVER FOR QXL VIRTUAL GPU, open list

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(-)

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);
-- 
2.18.1


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH v2] drm/qxl: get vga ioports
  2019-08-05 10:54 [PATCH v2] drm/qxl: get vga ioports Gerd Hoffmann
@ 2019-09-11 15:40 ` Frediano Ziglio
  0 siblings, 0 replies; 2+ messages in thread
From: Frediano Ziglio @ 2019-09-11 15:40 UTC (permalink / raw)
  To: Gerd Hoffmann
  Cc: dri-devel, Dave Airlie, David Airlie, Daniel Vetter,
	open list:DRM DRIVER FOR QXL VIRTUAL GPU,
	open list:DRM DRIVER FOR QXL VIRTUAL GPU, open list

> 
> 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

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2019-09-11 15:40 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-05 10:54 [PATCH v2] drm/qxl: get vga ioports Gerd Hoffmann
2019-09-11 15:40 ` Frediano Ziglio

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).