Re: Graphics pass-through

[Alex Williamson <alex.williamson@redhat.com>]

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On Thu, 2011-01-27 at 12:56 +0100, André Weidemann wrote:
> Hi Alex,
> 
> On 26.01.2011 06:12, Alex Williamson wrote:
> 
> > So while your initial results are promising, my guess is that you're
> > using card specific drivers and still need to consider some of the
> > harder problems with generic support for vga assignment.  I hacked on
> > this for a bit trying to see if I could get vga assignment working
> > with the vfio driver.  Setting up the legacy access and preventing
> > qemu from stealing it back should get you basic vga modes and might
> > even allow the option rom to run to initialize the card for pre-boot.
> > I was able to get this far on a similar ATI card.  I never hard much
> > luck with other cards though, and I was never able to get the vesa
> > extensions working.  Thanks,
> 
> Do you mind sharing these patches?

Attached.

Alex

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commit 0313d97cf24177023cdb6f2e4c54d077c5a775c1
Author: Alex Williamson <alex.williamson@redhat.com>
Date:   Wed Sep 29 13:50:39 2010 -0600

vfio: VGA passthrough support(ish)

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

diff --git a/Makefile.target b/Makefile.target
index c507dd2..cb0cea6 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -203,6 +203,7 @@ obj-i386-y += device-hotplug.o pci-hotplug.o smbios.o wdt_ib700.o
 obj-i386-y += debugcon.o multiboot.o
 obj-i386-y += pc_piix.o
 obj-i386-y += vfio.o
+obj-$(CONFIG_VFIO_VGA) += vfio-vga.o
 
 # shared objects
 obj-ppc-y = ppc.o
diff --git a/configure b/configure
index 3bfc5e9..b15e68f 100755
--- a/configure
+++ b/configure
@@ -322,6 +322,7 @@ user_pie="no"
 zero_malloc=""
 trace_backend="nop"
 trace_file="trace"
+vfio_vga="no"
 
 # OS specific
 if check_define __linux__ ; then
@@ -718,6 +719,8 @@ for opt do
   ;;
   --enable-vhost-net) vhost_net="yes"
   ;;
+  --enable-vfio-vga) vfio_vga="yes"
+  ;;
   --*dir)
   ;;
   *) echo "ERROR: unknown option $opt"; show_help="yes"
@@ -907,6 +910,7 @@ echo "  --disable-docs           disable documentation build"
 echo "  --disable-vhost-net      disable vhost-net acceleration support"
 echo "  --enable-vhost-net       enable vhost-net acceleration support"
 echo "  --trace-backend=B        Trace backend nop simple ust"
+echo "  --enable-vfio-vga        enable vfio VGA passthrough support"
 echo "  --trace-file=NAME        Full PATH,NAME of file to store traces"
 echo "                           Default:trace-<pid>"
 echo ""
@@ -2240,6 +2244,7 @@ echo "preadv support    $preadv"
 echo "fdatasync         $fdatasync"
 echo "uuid support      $uuid"
 echo "vhost-net support $vhost_net"
+echo "vfio-vga support  $vfio_vga"
 echo "Trace backend     $trace_backend"
 echo "Trace output file $trace_file-<pid>"
 
@@ -2762,6 +2767,9 @@ case "$target_arch2" in
     if test "$xen" = "yes" -a "$target_softmmu" = "yes" ; then
       echo "CONFIG_XEN=y" >> $config_target_mak
     fi
+    if test $vfio_vga = "yes" ; then
+      echo "CONFIG_VFIO_VGA=y" >> $config_host_mak
+    fi
 esac
 case "$target_arch2" in
   i386|x86_64|ppcemb|ppc|ppc64|s390x)
diff --git a/hw/vfio-vga.c b/hw/vfio-vga.c
new file mode 100644
index 0000000..5c1899c
--- /dev/null
+++ b/hw/vfio-vga.c
@@ -0,0 +1,291 @@
+/*
+ * vfio VGA device assignment support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Alex Williamson <alex.williamson@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Based on qemu-kvm device-assignment:
+ *  Adapted for KVM by Qumranet.
+ *  Copyright (c) 2007, Neocleus, Alex Novik (alex@neocleus.com)
+ *  Copyright (c) 2007, Neocleus, Guy Zana (guy@neocleus.com)
+ *  Copyright (C) 2008, Qumranet, Amit Shah (amit.shah@qumranet.com)
+ *  Copyright (C) 2008, Red Hat, Amit Shah (amit.shah@redhat.com)
+ *  Copyright (C) 2008, IBM, Muli Ben-Yehuda (muli@il.ibm.com)
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/io.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "event_notifier.h"
+#include "hw.h"
+#include "memory.h"
+#include "monitor.h"
+#include "pc.h"
+#include "qemu-error.h"
+#include "sysemu.h"
+#include "vfio.h"
+#include <pci/header.h>
+#include <pci/types.h>
+#include <linux/types.h>
+#include "linux-vfio.h"
+
+//#define DEBUG_VFIO_VGA
+#ifdef DEBUG_VFIO_VGA
+#define DPRINTF(fmt, ...) \
+    do { printf("vfio-vga: " fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+/*
+ * VGA setup
+ */
+static void vfio_vga_write(VFIODevice *vdev, uint32_t addr,
+                           uint32_t val, int len)
+{
+    DPRINTF("%s 0x%x %d - 0x%x\n", __func__, 0xa0000 + addr, len, val);
+    switch (len) {
+        case 1:
+            *(uint8_t *)(vdev->vga_mmio + addr) = (uint8_t)val;
+            break;
+        case 2:
+            *(uint16_t *)(vdev->vga_mmio + addr) = (uint16_t)val;
+            break;
+        case 4:
+            *(uint32_t *)(vdev->vga_mmio + addr) = val;
+            break;
+    }
+}
+
+static void vfio_vga_writeb(void *opaque, target_phys_addr_t addr, uint32_t val)
+{
+    vfio_vga_write(opaque, addr, val, 1);
+}
+
+static void vfio_vga_writew(void *opaque, target_phys_addr_t addr, uint32_t val)
+{
+    vfio_vga_write(opaque, addr, val, 2);
+}
+
+static void vfio_vga_writel(void *opaque, target_phys_addr_t addr, uint32_t val)
+{
+    vfio_vga_write(opaque, addr, val, 4);
+}
+
+static CPUWriteMemoryFunc * const vfio_vga_writes[] = {
+    &vfio_vga_writeb,
+    &vfio_vga_writew,
+    &vfio_vga_writel
+};
+
+static uint32_t vfio_vga_read(VFIODevice *vdev, uint32_t addr, int len)
+{
+    uint32_t val = 0xffffffff;
+    switch (len) {
+        case 1:
+            val = (uint32_t)*(uint8_t *)(vdev->vga_mmio + addr);
+            break;
+        case 2:
+            val = (uint32_t)*(uint16_t *)(vdev->vga_mmio + addr);
+            break;
+        case 4:
+            val = *(uint32_t *)(vdev->vga_mmio + addr);
+            break;
+    }
+    DPRINTF("%s 0x%x %d = 0x%x\n", __func__, 0xa0000 + addr, len, val);
+    return val;
+}
+
+static uint32_t vfio_vga_readb(void *opaque, target_phys_addr_t addr)
+{
+    return vfio_vga_read(opaque, addr, 1);
+}
+
+static uint32_t vfio_vga_readw(void *opaque, target_phys_addr_t addr)
+{
+    return vfio_vga_read(opaque, addr, 2);
+}
+
+static uint32_t vfio_vga_readl(void *opaque, target_phys_addr_t addr)
+{
+    return vfio_vga_read(opaque, addr, 4);
+}
+
+static CPUReadMemoryFunc * const vfio_vga_reads[] = {
+    &vfio_vga_readb,
+    &vfio_vga_readw,
+    &vfio_vga_readl
+};
+
+static void vfio_vga_out(VFIODevice *vdev, uint32_t addr, uint32_t val, int len)
+{
+    DPRINTF("%s 0x%x %d - 0x%x\n", __func__, addr, len, val);
+    ioperm(0x3b0, 0x30, 1); /* XXX fix me */
+    switch (len) {
+        case 1:
+            outb(val, addr);
+            break;
+        case 2:
+            outw(val, addr);
+            break;
+        case 4:
+            outl(val, addr);
+            break;
+    }
+}
+
+static void vfio_vga_outb(void *opaque, uint32_t addr, uint32_t val)
+{
+    vfio_vga_out(opaque, addr, val, 1);
+}
+
+static void vfio_vga_outw(void *opaque, uint32_t addr, uint32_t val)
+{
+    vfio_vga_out(opaque, addr, val, 2);
+}
+
+static void vfio_vga_outl(void *opaque, uint32_t addr, uint32_t val)
+{
+    vfio_vga_out(opaque, addr, val, 4);
+}
+
+static uint32_t vfio_vga_in(VFIODevice *vdev, uint32_t addr, int len)
+{
+    uint32_t val = 0xffffffff;
+    ioperm(0x3b0, 0x30, 1); /* XXX fix me */
+    switch (len) {
+        case 1:
+            val = inb(addr);
+            break;
+        case 2:
+            val = inw(addr);
+            break;
+        case 4:
+            val = inl(addr);
+            break;
+    }
+    DPRINTF("%s 0x%x, %d = 0x%x\n", __func__, addr, len, val);
+    return val;
+}
+
+static uint32_t vfio_vga_inb(void *opaque, uint32_t addr)
+{
+    return vfio_vga_in(opaque, addr, 1);
+}
+
+static uint32_t vfio_vga_inw(void *opaque, uint32_t addr)
+{
+    return vfio_vga_in(opaque, addr, 2);
+}
+
+static uint32_t vfio_vga_inl(void *opaque, uint32_t addr)
+{
+    return vfio_vga_in(opaque, addr, 4);
+}
+
+int vfio_vga_setup(VFIODevice *vdev)
+{
+    char buf[256];
+    int ret;
+
+    if (vga_interface_type != VGA_NONE) {
+        fprintf(stderr,
+                "VGA devie assigned without -vga none param, no ISA VGA\n");
+        return -1;
+    }
+
+    vdev->vga_fd = open("/dev/vga_arbiter", O_RDWR);
+    if (vdev->vga_fd < 0) {
+        fprintf(stderr, "%s - Failed to open vga arbiter (%s)\n",
+                __func__, strerror(errno));
+        return -1;
+    }
+    ret = read(vdev->vga_fd, buf, sizeof(buf));
+    if (ret <= 0) {
+        fprintf(stderr, "%s - Failed to read from vga arbiter (%s)\n",
+                __func__, strerror(errno));
+        close(vdev->vga_fd);
+        return -1;
+    }
+    buf[ret - 1] = 0;
+    vdev->vga_orig = qemu_strdup(buf);
+
+    snprintf(buf, sizeof(buf), "target PCI:%04x:%02x:%02x.%x",
+             vdev->host.seg, vdev->host.bus, vdev->host.dev, vdev->host.func);
+    ret = write(vdev->vga_fd, buf, strlen(buf));
+    if (ret != strlen(buf)) {
+        fprintf(stderr, "%s - Failed to write to vga arbiter (%s)\n",
+                __func__, strerror(errno));
+        close(vdev->vga_fd);
+        return -1;
+    }
+    snprintf(buf, sizeof(buf), "decodes io+mem");
+    ret = write(vdev->vga_fd, buf, strlen(buf));
+    if (ret != strlen(buf)) {
+        fprintf(stderr, "%s - Failed to write to vga arbiter (%s)\n",
+                __func__, strerror(errno));
+        close(vdev->vga_fd);
+        return -1;
+    }
+
+    vdev->vga_mmio_fd = open("/dev/mem", O_RDWR);
+    if (vdev->vga_mmio_fd < 0) {
+        fprintf(stderr, "%s - Failed to open /dev/mem (%s)\n",
+                __func__, strerror(errno));
+        return -1;
+    }
+    vdev->vga_mmio = mmap(NULL, 0x40000, PROT_READ | PROT_WRITE,
+                          MAP_SHARED, vdev->vga_mmio_fd, 0xa0000);
+    if (vdev->vga_mmio == MAP_FAILED) {
+        fprintf(stderr, "%s - mmap failed (%s)\n", __func__, strerror(errno));
+        return -1;
+    }
+
+#if 1
+    vdev->vga_io = cpu_register_io_memory(vfio_vga_reads,
+                                          vfio_vga_writes, vdev);
+    cpu_register_physical_memory(0xa0000, 0x20000, vdev->vga_io);
+    qemu_register_coalesced_mmio(0xa0000, 0x20000);
+#else
+    cpu_register_physical_memory(0xa0000, 0x20000, 
+        qemu_ram_map(&vdev->pdev.qdev, "VGA", 0x20000, vdev->vga_mmio));
+    qemu_register_coalesced_mmio(0xa0000, 0x20000);
+#endif
+
+    register_ioport_write(0x3b0, 0x30, 1, vfio_vga_outb, vdev);
+    register_ioport_write(0x3b0, 0x30, 2, vfio_vga_outw, vdev);
+    register_ioport_write(0x3b0, 0x30, 4, vfio_vga_outl, vdev);
+    register_ioport_read(0x3b0, 0x30, 1, vfio_vga_inb, vdev);
+    register_ioport_read(0x3b0, 0x30, 2, vfio_vga_inw, vdev);
+    register_ioport_read(0x3b0, 0x30, 4, vfio_vga_inl, vdev);
+    if (ioperm(0x3b0, 0x30, 1)) {
+        fprintf(stderr, "%s - ioperm failed (%s)\n", __func__, strerror(errno));
+        return -1;
+    }
+    return 0;
+}
+
+void vfio_vga_exit(VFIODevice *vdev)
+{
+    if (!vdev->vga_io)
+        return;
+
+    isa_unassign_ioport(0x3b0, 0x30);
+    qemu_unregister_coalesced_mmio(0xa0000, 0x20000);
+    cpu_register_physical_memory(0xa0000, 0x20000, IO_MEM_UNASSIGNED);
+    cpu_unregister_io_memory(vdev->vga_io);
+    munmap(vdev->vga_mmio, 0x40000);
+    close(vdev->vga_mmio_fd);
+    qemu_free(vdev->vga_orig);
+    close(vdev->vga_fd);
+}
+
diff --git a/hw/vfio.c b/hw/vfio.c
index e2da724..f7c7a42 100644
--- a/hw/vfio.c
+++ b/hw/vfio.c
@@ -1268,8 +1268,22 @@ static int vfio_initfn(struct PCIDevice *pdev)
     if (vfio_enable_intx(vdev))
         goto out_unmap_iommu;
 
+#ifdef CONFIG_VFIO_VGA
+    {
+        uint16_t class;
+
+        class = vfio_pci_read_config(&vdev->pdev, PCI_CLASS_DEVICE, 2);
+        if (class == PCI_CLASS_DISPLAY_VGA && vfio_vga_setup(vdev))
+            goto out_vga_fail;
+    }
+#endif
+
     return 0;
 
+#ifdef CONFIG_VFIO_VGA
+out_vga_fail:
+    vfio_disable_intx(vdev);
+#endif
 out_unmap_iommu:
     vfio_unmap_iommu(vdev);
 out_unmap_resources:
@@ -1290,6 +1304,9 @@ static int vfio_exitfn(struct PCIDevice *pdev)
 {
     VFIODevice *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
     
+#ifdef CONFIG_VFIO_VGA
+    vfio_vga_exit(vdev);
+#endif
     vfio_disable_intx(vdev);
     vfio_disable_msi(vdev);
     vfio_disable_msix(vdev);
diff --git a/hw/vfio.h b/hw/vfio.h
index b5a0525..c7490b3 100644
--- a/hw/vfio.h
+++ b/hw/vfio.h
@@ -83,8 +83,20 @@ typedef struct VFIODevice {
     MSIX msix;
     int vfiofd;
     int uiommufd;
+#ifdef CONFIG_VFIO_VGA
+    int vga_io;
+    int vga_fd;
+    int vga_mmio_fd;
+    uint8_t *vga_mmio;
+    char *vga_orig;
+#endif
     char *vfiofd_name;
     char *uiommufd_name;
 } VFIODevice;
 
+#ifdef CONFIG_VFIO_VGA
+int vfio_vga_setup(VFIODevice *vdev);
+void vfio_vga_exit(VFIODevice *vdev);
+#endif
+
 #endif /* __VFIO_H__ */