Re: [Qemu-devel] [Xen-devel] [PATCH V4 05/10] Introduce HostPCIDevice to access a pci device on the host.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Nov 17, 2011 at 03:17:08PM +0000, Anthony PERARD wrote:
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>  Makefile.target      |    1 +
>  hw/host-pci-device.c |  279 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/host-pci-device.h |   75 ++++++++++++++
>  3 files changed, 355 insertions(+), 0 deletions(-)
>  create mode 100644 hw/host-pci-device.c
>  create mode 100644 hw/host-pci-device.h
> 
> diff --git a/Makefile.target b/Makefile.target
> index 2e881ce..e527c1b 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -220,6 +220,7 @@ obj-$(CONFIG_NO_XEN) += xen-stub.o
>  obj-i386-$(CONFIG_XEN) += xen_platform.o
>  
>  # Xen PCI Passthrough
> +obj-i386-$(CONFIG_XEN_PCI_PASSTHROUGH) += host-pci-device.o
>  
>  # Inter-VM PCI shared memory
>  CONFIG_IVSHMEM =
> diff --git a/hw/host-pci-device.c b/hw/host-pci-device.c
> new file mode 100644
> index 0000000..06f7761
> --- /dev/null
> +++ b/hw/host-pci-device.c
> @@ -0,0 +1,279 @@
> +/*
> + * Copyright (C) 2011       Citrix Ltd.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.  See
> + * the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu-common.h"
> +#include "host-pci-device.h"
> +
> +#define PCI_MAX_EXT_CAP \
> +    ((PCIE_CONFIG_SPACE_SIZE - PCI_CONFIG_SPACE_SIZE) / (PCI_CAP_SIZEOF + 4))
> +
> +enum error_code {
> +    ERROR_SYNTAX = 1,
> +};
> +
> +static int path_to(const HostPCIDevice *d,
> +                   const char *name, char *buf, ssize_t size)
> +{
> +    return snprintf(buf, size, "/sys/bus/pci/devices/%04x:%02x:%02x.%x/%s",
> +                    d->domain, d->bus, d->dev, d->func, name);
> +}
> +
> +static int get_resource(HostPCIDevice *d)
> +{
> +    int i, rc = 0;
> +    FILE *f;
> +    char path[PATH_MAX];
> +    unsigned long long start, end, flags, size;
> +
> +    path_to(d, "resource", path, sizeof (path));
> +    f = fopen(path, "r");
> +    if (!f) {
> +        fprintf(stderr, "Error: Can't open %s: %s\n", path, strerror(errno));
> +        return -errno;
> +    }
> +
> +    for (i = 0; i < PCI_NUM_REGIONS; i++) {
> +        if (fscanf(f, "%llx %llx %llx", &start, &end, &flags) != 3) {
> +            fprintf(stderr, "Error: Syntax error in %s\n", path);
> +            rc = ERROR_SYNTAX;
> +            break;
> +        }
> +        if (start) {
> +            size = end - start + 1;
> +        } else {
> +            size = 0;
> +        }
> +
> +        if (i < PCI_ROM_SLOT) {
> +            d->io_regions[i].base_addr = start;
> +            d->io_regions[i].size = size;
> +            d->io_regions[i].flags = flags;
> +        } else {
> +            d->rom.base_addr = start;
> +            d->rom.size = size;
> +            d->rom.flags = flags;
> +        }
> +    }
> +
> +    fclose(f);
> +    return rc;
> +}
> +
> +static int get_value(HostPCIDevice *d, const char *name, unsigned long *pvalue)

Perhaps 'get_hex_value'? You are just doing %lx, not %ld, so it has
to have to an exact format to get the contents right.

> +{
> +    char path[PATH_MAX];
> +    FILE *f;
> +    unsigned long value;
> +
> +    path_to(d, name, path, sizeof (path));
> +    f = fopen(path, "r");
> +    if (!f) {
> +        fprintf(stderr, "Error: Can't open %s: %s\n", path, strerror(errno));
> +        return -1;

So the get_resource can return 0, 1, or -errno. This one can return
0, or -1. Would it make sense to duplicate the -errno mechanism
that you employed in get_resources to have uniformity?

> +    }
> +    if (fscanf(f, "%lx\n", &value) != 1) {
> +        fprintf(stderr, "Error: Syntax error in %s\n", path);
> +        return -1;
> +    }
> +    fclose(f);
> +    *pvalue = value;
> +    return 0;
> +}
> +
> +static bool pci_dev_is_virtfn(HostPCIDevice *d)
> +{
> +    int rc;
> +    char path[PATH_MAX];
> +    struct stat buf;
> +
> +    path_to(d, "physfn", path, sizeof (path));
> +    rc = !stat(path, &buf);
> +
> +    return rc;
> +}
> +
> +static int host_pci_config_fd(HostPCIDevice *d)
> +{
> +    char path[PATH_MAX];
> +
> +    if (d->config_fd < 0) {
> +        path_to(d, "config", path, sizeof (path));
> +        d->config_fd = open(path, O_RDWR);
> +        if (d->config_fd < 0) {
> +            fprintf(stderr, "HostPCIDevice: Can not open '%s': %s\n",
> +                    path, strerror(errno));
> +        }
> +    }
> +    return d->config_fd;
> +}
> +static int host_pci_config_read(HostPCIDevice *d, int pos, void *buf, int len)
> +{
> +    int fd = host_pci_config_fd(d);
> +    int res = 0;
> +
> +again:
> +    res = pread(fd, buf, len, pos);
> +    if (res != len) {
> +        if (res < 0 && (errno == EINTR || errno == EAGAIN)) {
> +            goto again;
> +        }
> +        fprintf(stderr, "host_pci_config: read failed: %s (fd: %i)\n",

Well, the comment says 'host_pci_config', but that is not the name
of the function. Perhaps replace it with '%s' and use __func__
as one of the parameters?

> +                strerror(errno), fd);
> +        return -errno;
> +    }
> +    return 0;
> +}
> +static int host_pci_config_write(HostPCIDevice *d,
> +                                 int pos, const void *buf, int len)
> +{
> +    int fd = host_pci_config_fd(d);
> +    int res = 0;
> +
> +again:
> +    res = pwrite(fd, buf, len, pos);
> +    if (res != len) {
> +        if (res < 0 && (errno == EINTR || errno == EAGAIN)) {
> +            goto again;
> +        }
> +        fprintf(stderr, "host_pci_config: write failed: %s\n",
> +                strerror(errno));
> +        return -errno;
> +    }
> +    return 0;
> +}
> +
> +int host_pci_get_byte(HostPCIDevice *d, int pos, uint8_t *p)
> +{
> +  uint8_t buf;
> +  if (host_pci_config_read(d, pos, &buf, 1)) {
> +      return -1;

Would it make sense to use the nice enum you decleraed at the
top of the file?  Or not?