Re: ioperm problem

[Ben Guthro <ben.guthro@virtualcomputer.com>]

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Attached is our patch to work around issues with the ioports with some 
older nVidia cards.

This, admittedly is a bit of a hack, and not exactly something that I 
would see upstream wanting to carry, for a variety of reasons. It really 
should all be predicated on whether the kernel is the initial domain, etc.

This opens up the legacy VGA ports in the VGA arbiter code.

Konrad - I think that you had suggested an alternate way of doing this, 
IIRC, but I can't seem to find it in my inbox. Due to competing demands, 
and my nVidia hardware disappearing, I never went back to rework this code.

As written, however, it did solve the problem at hand - however hacky it 
may be.

/btg

On 11/16/2011 09:57 AM, Konrad Rzeszutek Wilk wrote:
> On Sun, Nov 13, 2011 at 10:19:06PM +0100, Pavel Matěja wrote:
>> Hi,
>> I'm trying to port AMD VGA passthru patch to the latest XEN and vanila kernel
>> and I got SIGSEGV in
>>
>> static void ati_hw_out(uint16_t hport, uint32_t data)
>> {
>>      ioperm(gfx_info.host_pio_base, gfx_info.pio_size, 1);
>>      asm volatile ("out %1, %0"::"Nd"(hport),"a"(data));
>>      ioperm(gfx_info.host_pio_base, gfx_info.pio_size, 0);
>> }
>
> Does it work under baremetal?
>
> What is the host_pio_base?
>
> Is the host_pio_base part of the permitted IO ports? (you can
> see that if you run 'xl debug-keys q' and it should show you something
> like this:
>
> (XEN) Rangesets belonging to domain 1:
> (XEN)     I/O Ports  { b400-b41f, b800-b81f }
> (XEN)     Interrupts { 18-19, 54-55 }
> (XEN)     I/O Memory { fe940-fe9ff }
> (XEN) Memory pages belonging to domain 1:
>
> (you can get that from xm dmesg).
>
> As you can see, the b400->b41f are allowed in the domain 1. Is your
> host_pio_base in there?
>
>
>>
>> I tried old 2.6.32 XEN kernel and there is no such problem.
>> It looks related to arch/x86/kernel/ioport.c but I'm not sure.
>> Is anyone here familiar with that code?
>
> Yes, and I think I saw somebody ask me about that too.
>
> Lets rope them in this converstation - they got it to work
> but my memory is foggy at what was required.
>
> Ben, Thomas,
>
> I remember you guys had a tough time with vd86 which did something similar
> and it ultimately was due to to /dev/mem not passing in VM_IO. But the
> ioperm/outb sounds familiar too. Was there a missing hypercall when
> forking/copying the ioperm bitmap?

[-- Attachment #2: vga-ioport-enable.patch --]
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diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index ace2b16..d488426 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -421,6 +421,50 @@ bail:
 }
 EXPORT_SYMBOL(vga_put);
 
+#ifdef CONFIG_XEN
+#include <xen/xen.h>
+#include <xen/interface/physdev.h>
+#include <xen/interface/xen.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+#define IO_BITMAP_BITS 65536
+#define IO_BITMAP_BYTES (IO_BITMAP_BITS/8)
+
+#define VGA_START_PORT 0x3B0
+#define VGA_END_PORT 0x3DF
+
+static void
+vga_ioport_map(struct pci_dev *pdev)
+{
+	unsigned int i, j;
+	struct physdev_set_iobitmap op;
+	uint8_t *bitmap;
+
+	bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
+	memset(bitmap, 0xff, IO_BITMAP_BYTES);
+
+	/* PCI io bars */
+	for (i = 0; i < PCI_NUM_RESOURCES; i++)
+		if (pci_resource_flags(pdev, i) & IORESOURCE_IO)
+			for (j = pci_resource_start(pdev, i);
+				j <= pci_resource_end(pdev, i); j++)
+				__clear_bit(j, (unsigned long*)bitmap);
+
+	/* legacy vga */
+	for (i = VGA_START_PORT; i <= VGA_END_PORT; i++)
+		__clear_bit(i, (unsigned long*)bitmap);
+
+	op.bitmap = bitmap;
+	op.nr_ports = IO_BITMAP_BITS;
+	if(HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &op) != 0)
+		pr_info("PHYSDEVOP_set_iobitmap failed\n");
+
+}
+#else
+#define vga_ioport_map(x)
+#endif
+
 /*
  * Currently, we assume that the "initial" setup of the system is
  * not sane, that is we come up with conflicting devices and let
@@ -509,6 +553,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 		vga_iostate_to_str(vgadev->owns),
 		vga_iostate_to_str(vgadev->locks));
 
+	vga_ioport_map(pdev);
 	spin_unlock_irqrestore(&vga_lock, flags);
 	return true;
 fail:

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