Re: [Qemu-devel] [PATCH 4/5] xen, gfx passthrough: support Intel IGD passthrough with VT-D

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

CC'ing Michael.

On Fri, 21 Feb 2014, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@Intel.com>
> 
> Some registers of Intel IGD are mapped in host bridge, so it needs to
> passthrough these registers of physical host bridge to guest because
> emulated host bridge in guest doesn't have these mappings.
> 
> The original patch is from Weidong Han < weidong.han @ intel.com >
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> Cc:Weidong Han <weidong.han@intel.com>
> ---
>  hw/pci-host/piix.c       |   15 ++++++
>  hw/pci/pci.c             |   13 +++++
>  hw/xen/xen_pt.h          |    5 ++
>  hw/xen/xen_pt_graphics.c |  127 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 160 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> index ffdc853..68cf756 100644
> --- a/hw/pci-host/piix.c
> +++ b/hw/pci-host/piix.c
> @@ -34,6 +34,9 @@
>  #include "sysemu/sysemu.h"
>  #include "hw/i386/ioapic.h"
>  #include "qapi/visitor.h"
> +#if defined(CONFIG_XEN_PCI_PASSTHROUGH)
> +#include "hw/xen/xen_pt.h"
> +#endif
>  
>  /*
>   * I440FX chipset data sheet.
> @@ -389,6 +392,18 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state,
>  
>      i440fx_update_memory_mappings(f);
>  
> +#if defined(CONFIG_XEN_PCI_PASSTHROUGH)
> +    /*
> +     * Some registers of Intel IGD are mapped in host bridge, so it needs to
> +     * passthrough these registers of physical host bridge to guest because
> +     * emulated host bridge in guest doesn't have these mappings.
> +     */
> +    if (intel_pch_init(b) == 0) {
> +        d->config_read = igd_pci_read;
> +        d->config_write = igd_pci_write;
> +    }
> +#endif

I can't see the other QEMU maintainers being happy with these changes.
Michael, do you have a suggestion on how to do this in a better way?


>      return b;
>  }
>  
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index e81816e..7016b71 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -36,6 +36,9 @@
>  #include "hw/pci/msix.h"
>  #include "exec/address-spaces.h"
>  #include "hw/hotplug.h"
> +#if defined(CONFIG_XEN_PCI_PASSTHROUGH)
> +#include "hw/xen/xen_pt.h"
> +#endif
>  
>  //#define DEBUG_PCI
>  #ifdef DEBUG_PCI
> @@ -805,6 +808,16 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
>      PCIConfigWriteFunc *config_write = pc->config_write;
>      AddressSpace *dma_as;
>  
> +#if defined(CONFIG_XEN_PCI_PASSTHROUGH)
> +    /*
> +     * Some video bioses and gfx drivers will assume the bdf of IGD is 00:02.0.
> +     * So user need to set it to 00:02.0 in Xen configure file explicitly,
> +     * otherwise IGD will fail to work.
> +     */
> +    if (gfx_passthru && devfn == 0x10)
> +        igd_passthru = 1;
> +    else
> +#endif
>      if (devfn < 0) {
>          for(devfn = bus->devfn_min ; devfn < ARRAY_SIZE(bus->devices);
>              devfn += PCI_FUNC_MAX) {

Same here


> diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
> index c04bbfd..92e4d51 100644
> --- a/hw/xen/xen_pt.h
> +++ b/hw/xen/xen_pt.h
> @@ -299,8 +299,13 @@ static inline bool xen_pt_has_msix_mapping(XenPCIPassthroughState *s, int bar)
>  }
>  
>  extern int gfx_passthru;
> +extern int igd_passthru;
>  int register_vga_regions(XenHostPCIDevice *dev);
>  int unregister_vga_regions(XenHostPCIDevice *dev);
>  int setup_vga_pt(XenHostPCIDevice *dev);
> +int intel_pch_init(PCIBus *bus);
> +void igd_pci_write(PCIDevice *pci_dev, uint32_t config_addr,
> +                   uint32_t val, int len);
> +uint32_t igd_pci_read(PCIDevice *pci_dev, uint32_t config_addr, int len);
>  
>  #endif /* !XEN_PT_H */
> diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
> index 54f16cf..2a01406 100644
> --- a/hw/xen/xen_pt_graphics.c
> +++ b/hw/xen/xen_pt_graphics.c
> @@ -5,6 +5,8 @@
>  #include "xen-host-pci-device.h"
>  #include "hw/xen/xen_backend.h"
>  
> +int igd_passthru;
> +
>  /*
>   * register VGA resources for the domain with assigned gfx
>   */
> @@ -233,3 +235,128 @@ static int create_pch_isa_bridge(PCIBus *bus, XenHostPCIDevice *hdev)
>      XEN_PT_LOG(dev, "Intel PCH ISA bridge is created.\n");
>      return 0;
>  }
> +
> +int intel_pch_init(PCIBus *bus)
> +{
> +    XenHostPCIDevice hdev;
> +    int r = 0;
> +
> +    if (!gfx_passthru) {
> +        return -1;
> +    }
> +
> +    r = xen_host_pci_device_get(&hdev, 0, 0, 0x1f, 0);
> +    if (r) {
> +        XEN_PT_ERR(NULL, "Fail to find intel PCH in host\n");
> +        goto err;
> +    }
> +
> +    if (hdev.vendor_id == PCI_VENDOR_ID_INTEL) {
> +        r = create_pch_isa_bridge(bus, &hdev);
> +        if (r) {
> +            XEN_PT_ERR(NULL, "Fail to create PCH ISA bridge.\n");
> +            goto err;
> +        }
> +    }
> +
> +    xen_host_pci_device_put(&hdev);
> +
> +    return  r;
> +
> +err:
> +    return r;
> +}
> +
> +void igd_pci_write(PCIDevice *pci_dev, uint32_t config_addr,
> +                   uint32_t val, int len)
> +{
> +    XenHostPCIDevice dev;
> +    int r;
> +
> +    assert(pci_dev->devfn == 0x00);
> +
> +    if (!igd_passthru) {
> +        goto write_default;
> +    }
> +
> +    switch (config_addr) {
> +    case 0x58:      /* PAVPC Offset */
> +        break;
> +    default:
> +        goto write_default;
> +    }
> +
> +    /* Host write */
> +    r = xen_host_pci_device_get(&dev, 0, 0, 0, 0);
> +    if (r) {
> +        XEN_PT_ERR(pci_dev, "Can't get pci_dev_host_bridge\n");
> +        abort();
> +    }
> +
> +    r = xen_host_pci_set_block(&dev, config_addr, (uint8_t *)&val, len);
> +    if (r) {
> +        XEN_PT_ERR(pci_dev, "Can't get pci_dev_host_bridge\n");
> +        abort();
> +    }
> +
> +    xen_host_pci_device_put(&dev);
> +
> +    return;
> +
> +write_default:
> +    pci_default_write_config(pci_dev, config_addr, val, len);
> +}
> +
> +uint32_t igd_pci_read(PCIDevice *pci_dev, uint32_t config_addr, int len)
> +{
> +    XenHostPCIDevice dev;
> +    uint32_t val;
> +    int r;
> +
> +    assert(pci_dev->devfn == 0x00);
> +
> +    if (!igd_passthru) {
> +        goto read_default;
> +    }
> +
> +    switch (config_addr) {
> +    case 0x00:        /* vendor id */
> +    case 0x02:        /* device id */
> +    case 0x08:        /* revision id */
> +    case 0x2c:        /* sybsystem vendor id */
> +    case 0x2e:        /* sybsystem id */
> +    case 0x50:        /* SNB: processor graphics control register */
> +    case 0x52:        /* processor graphics control register */
> +    case 0xa0:        /* top of memory */
> +    case 0xb0:        /* ILK: BSM: should read from dev 2 offset 0x5c */
> +    case 0x58:        /* SNB: PAVPC Offset */
> +    case 0xa4:        /* SNB: graphics base of stolen memory */
> +    case 0xa8:        /* SNB: base of GTT stolen memory */
> +        break;
> +    default:
> +        goto read_default;
> +    }
> +
> +    /* Host read */
> +    r = xen_host_pci_device_get(&dev, 0, 0, 0, 0);
> +    if (r) {
> +        goto err_out;
> +    }
> +
> +    r = xen_host_pci_get_block(&dev, config_addr, (uint8_t *)&val, len);
> +    if (r) {
> +        goto err_out;
> +    }
> +
> +    xen_host_pci_device_put(&dev);
> +
> +    return val;
> +
> +read_default:
> +    return pci_default_read_config(pci_dev, config_addr, len);
> +
> +err_out:
> +    XEN_PT_ERR(pci_dev, "Can't get pci_dev_host_bridge\n");
> +    return -1;
> +}

The Xen specific part is OK.