Re: [Xen-devel] [PATCH] xen-hvm: stop faking I/O to access PCI config space

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, May 03, 2018 at 12:18:40PM +0100, Paul Durrant wrote:
> This patch removes the current hackery where IOREQ_TYPE_PCI_CONFIG
> reqyests are handled by faking PIO to 0xcf8 and 0xcfc and replaces it
> with direct calls to pci_host_config_read/write_common().
> Doing so necessitates mapping BDFs to PCIDevices but maintaining a simple
> QLIST in xen_device_realize/unrealize() will suffice.
> 
> NOTE: whilst config space accesses are currently limited to
>       PCI_CONFIG_SPACE_SIZE, this patch paves the way to increasing the
>       limit to PCIE_CONFIG_SPACE_SIZE when Xen gains the ability to
>       emulate MCFG table accesses.

Thanks for doing this. I'm not a QEMU maintainer but:

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> --
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Anthony Perard <anthony.perard@xxxxxxxxxx>
> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> Cc: Marcel Apfelbaum <marcel@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Richard Henderson <rth@xxxxxxxxxxx>
> Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx>
> ---
>  hw/i386/xen/trace-events |   2 +
>  hw/i386/xen/xen-hvm.c    | 101 
> +++++++++++++++++++++++++++++++++++++----------
>  2 files changed, 83 insertions(+), 20 deletions(-)
> 
> diff --git a/hw/i386/xen/trace-events b/hw/i386/xen/trace-events
> index 8dab7bc..f576f1b 100644
> --- a/hw/i386/xen/trace-events
> +++ b/hw/i386/xen/trace-events
> @@ -15,6 +15,8 @@ cpu_ioreq_pio(void *req, uint32_t dir, uint32_t df, 
> uint32_t data_is_ptr, uint64
>  cpu_ioreq_pio_read_reg(void *req, uint64_t data, uint64_t addr, uint32_t 
> size) "I/O=%p pio read reg data=0x%"PRIx64" port=0x%"PRIx64" size=%d"
>  cpu_ioreq_pio_write_reg(void *req, uint64_t data, uint64_t addr, uint32_t 
> size) "I/O=%p pio write reg data=0x%"PRIx64" port=0x%"PRIx64" size=%d"
>  cpu_ioreq_move(void *req, uint32_t dir, uint32_t df, uint32_t data_is_ptr, 
> uint64_t addr, uint64_t data, uint32_t count, uint32_t size) "I/O=%p copy 
> dir=%d df=%d ptr=%d port=0x%"PRIx64" data=0x%"PRIx64" count=%d size=%d"
> +cpu_ioreq_config_read(void *req, uint32_t sbdf, uint32_t reg, uint32_t size, 
> uint32_t data) "I/O=%p sbdf=0x%x reg=%u size=%u data=0x%x"
> +cpu_ioreq_config_write(void *req, uint32_t sbdf, uint32_t reg, uint32_t 
> size, uint32_t data) "I/O=%p sbdf=0x%x reg=%u size=%u data=0x%x"
>  
>  # xen-mapcache.c
>  xen_map_cache(uint64_t phys_addr) "want 0x%"PRIx64
> diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
> index caa563b..c139d29 100644
> --- a/hw/i386/xen/xen-hvm.c
> +++ b/hw/i386/xen/xen-hvm.c
> @@ -12,6 +12,7 @@
>  
>  #include "cpu.h"
>  #include "hw/pci/pci.h"
> +#include "hw/pci/pci_host.h"
>  #include "hw/i386/pc.h"
>  #include "hw/i386/apic-msidef.h"
>  #include "hw/xen/xen_common.h"
> @@ -86,6 +87,12 @@ typedef struct XenPhysmap {
>      QLIST_ENTRY(XenPhysmap) list;
>  } XenPhysmap;
>  
> +typedef struct XenPciDevice {
> +    PCIDevice *pci_dev;
> +    uint32_t sbdf;
> +    QLIST_ENTRY(XenPciDevice) entry;
> +} XenPciDevice;
> +
>  typedef struct XenIOState {
>      ioservid_t ioservid;
>      shared_iopage_t *shared_page;
> @@ -105,6 +112,7 @@ typedef struct XenIOState {
>      struct xs_handle *xenstore;
>      MemoryListener memory_listener;
>      MemoryListener io_listener;
> +    QLIST_HEAD(, XenPciDevice) dev_list;
>      DeviceListener device_listener;
>      QLIST_HEAD(, XenPhysmap) physmap;
>      hwaddr free_phys_offset;
> @@ -569,6 +577,12 @@ static void xen_device_realize(DeviceListener *listener,
>  
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
>          PCIDevice *pci_dev = PCI_DEVICE(dev);
> +        XenPciDevice *xendev = g_new(XenPciDevice, 1);
> +
> +        xendev->pci_dev = pci_dev;
> +        xendev->sbdf = PCI_BUILD_BDF(pci_dev_bus_num(pci_dev),
> +                                     pci_dev->devfn);
> +        QLIST_INSERT_HEAD(&state->dev_list, xendev, entry);
>  
>          xen_map_pcidev(xen_domid, state->ioservid, pci_dev);
>      }
> @@ -581,8 +595,17 @@ static void xen_device_unrealize(DeviceListener 
> *listener,
>  
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
>          PCIDevice *pci_dev = PCI_DEVICE(dev);
> +        XenPciDevice *xendev, *next;
>  
>          xen_unmap_pcidev(xen_domid, state->ioservid, pci_dev);
> +
> +        QLIST_FOREACH_SAFE(xendev, &state->dev_list, entry, next) {
> +            if (xendev->pci_dev == pci_dev) {
> +                QLIST_REMOVE(xendev, entry);
> +                g_free(xendev);
> +                break;
> +            }
> +        }
>      }
>  }
>  
> @@ -903,6 +926,61 @@ static void cpu_ioreq_move(ioreq_t *req)
>      }
>  }
>  
> +static void cpu_ioreq_config(XenIOState *state, ioreq_t *req)
> +{
> +    uint32_t sbdf = req->addr >> 32;
> +    uint32_t reg = req->addr;
> +    XenPciDevice *xendev;
> +
> +    if (req->size > sizeof(uint32_t)) {
> +        hw_error("PCI config access: bad size (%u)", req->size);
> +    }
> +
> +    QLIST_FOREACH(xendev, &state->dev_list, entry) {
> +        unsigned int i;
> +
> +        if (xendev->sbdf != sbdf) {
> +            continue;
> +        }
> +
> +        if (req->dir == IOREQ_READ) {

I would have used a switch here, but that's just personal taste.

Roger.

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