Hi, Paul!
On 11/24/20 10:01 AM, Paul Durrant wrote:
> From: Paul Durrant <pdurrant@amazon.com>
>
> Use of this function is a very inefficient way to check whether a device
> has already been assigned.
>
> This patch adds code that saves the domain id in xenstore at the point of
> assignment, and removes it again when the device id de-assigned (or the
> domain is destroyed). It is then straightforward to check whether a device
> has been assigned by checking whether a device has a saved domain id.
>
> NOTE: To facilitate the xenstore check it is necessary to move the
> pci_info_xs_read() earlier in libxl_pci.c. To keep related functions
> together, the rest of the pci_info_xs_XXX() functions are moved too.
>
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Thank you,
Oleksandr
> ---
> Cc: Ian Jackson <iwj@xenproject.org>
> Cc: Wei Liu <wl@xen.org>
> ---
> tools/libs/light/libxl_pci.c | 149 ++++++++++++++++---------------------------
> 1 file changed, 55 insertions(+), 94 deletions(-)
>
> diff --git a/tools/libs/light/libxl_pci.c b/tools/libs/light/libxl_pci.c
> index ec101f255f..d3c7a547c3 100644
> --- a/tools/libs/light/libxl_pci.c
> +++ b/tools/libs/light/libxl_pci.c
> @@ -336,50 +336,6 @@ retry_transaction2:
> return 0;
> }
>
> -static int get_all_assigned_devices(libxl__gc *gc, libxl_device_pci **list, int *num)
> -{
> - char **domlist;
> - unsigned int nd = 0, i;
> -
> - *list = NULL;
> - *num = 0;
> -
> - domlist = libxl__xs_directory(gc, XBT_NULL, "/local/domain", &nd);
> - for(i = 0; i < nd; i++) {
> - char *path, *num_devs;
> -
> - path = GCSPRINTF("/local/domain/0/backend/%s/%s/0/num_devs",
> - libxl__device_kind_to_string(LIBXL__DEVICE_KIND_PCI),
> - domlist[i]);
> - num_devs = libxl__xs_read(gc, XBT_NULL, path);
> - if ( num_devs ) {
> - int ndev = atoi(num_devs), j;
> - char *devpath, *bdf;
> -
> - for(j = 0; j < ndev; j++) {
> - devpath = GCSPRINTF("/local/domain/0/backend/%s/%s/0/dev-%u",
> - libxl__device_kind_to_string(LIBXL__DEVICE_KIND_PCI),
> - domlist[i], j);
> - bdf = libxl__xs_read(gc, XBT_NULL, devpath);
> - if ( bdf ) {
> - unsigned dom, bus, dev, func;
> - if ( sscanf(bdf, PCI_BDF, &dom, &bus, &dev, &func) != 4 )
> - continue;
> -
> - *list = realloc(*list, sizeof(libxl_device_pci) * ((*num) + 1));
> - if (*list == NULL)
> - return ERROR_NOMEM;
> - pci_struct_fill(*list + *num, dom, bus, dev, func, 0);
> - (*num)++;
> - }
> - }
> - }
> - }
> - libxl__ptr_add(gc, *list);
> -
> - return 0;
> -}
> -
> static int is_pci_in_array(libxl_device_pci *assigned, int num_assigned,
> int dom, int bus, int dev, int func)
> {
> @@ -427,19 +383,58 @@ static int sysfs_write_bdf(libxl__gc *gc, const char * sysfs_path,
> return 0;
> }
>
> +#define PCI_INFO_PATH "/libxl/pci"
> +
> +static char *pci_info_xs_path(libxl__gc *gc, libxl_device_pci *pci,
> + const char *node)
> +{
> + return node ?
> + GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH"/%s",
> + pci->domain, pci->bus, pci->dev, pci->func,
> + node) :
> + GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH,
> + pci->domain, pci->bus, pci->dev, pci->func);
> +}
> +
> +
> +static int pci_info_xs_write(libxl__gc *gc, libxl_device_pci *pci,
> + const char *node, const char *val)
> +{
> + char *path = pci_info_xs_path(gc, pci, node);
> + int rc = libxl__xs_printf(gc, XBT_NULL, path, "%s", val);
> +
> + if (rc) LOGE(WARN, "Write of %s to node %s failed.", val, path);
> +
> + return rc;
> +}
> +
> +static char *pci_info_xs_read(libxl__gc *gc, libxl_device_pci *pci,
> + const char *node)
> +{
> + char *path = pci_info_xs_path(gc, pci, node);
> +
> + return libxl__xs_read(gc, XBT_NULL, path);
> +}
> +
> +static void pci_info_xs_remove(libxl__gc *gc, libxl_device_pci *pci,
> + const char *node)
> +{
> + char *path = pci_info_xs_path(gc, pci, node);
> + libxl_ctx *ctx = libxl__gc_owner(gc);
> +
> + /* Remove the xenstore entry */
> + xs_rm(ctx->xsh, XBT_NULL, path);
> +}
> +
> libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
> {
> GC_INIT(ctx);
> - libxl_device_pci *pcis = NULL, *new, *assigned;
> + libxl_device_pci *pcis = NULL, *new;
> struct dirent *de;
> DIR *dir;
> - int r, num_assigned;
>
> *num = 0;
>
> - r = get_all_assigned_devices(gc, &assigned, &num_assigned);
> - if (r) goto out;
> -
> dir = opendir(SYSFS_PCIBACK_DRIVER);
> if (NULL == dir) {
> if (errno == ENOENT) {
> @@ -455,9 +450,6 @@ libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
> if (sscanf(de->d_name, PCI_BDF, &dom, &bus, &dev, &func) != 4)
> continue;
>
> - if (is_pci_in_array(assigned, num_assigned, dom, bus, dev, func))
> - continue;
> -
> new = realloc(pcis, ((*num) + 1) * sizeof(*new));
> if (NULL == new)
> continue;
> @@ -467,6 +459,10 @@ libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
>
> memset(new, 0, sizeof(*new));
> pci_struct_fill(new, dom, bus, dev, func, 0);
> +
> + if (pci_info_xs_read(gc, new, "domid")) /* already assigned */
> + continue;
> +
> (*num)++;
> }
>
> @@ -737,48 +733,6 @@ static int pciback_dev_unassign(libxl__gc *gc, libxl_device_pci *pci)
> return 0;
> }
>
> -#define PCI_INFO_PATH "/libxl/pci"
> -
> -static char *pci_info_xs_path(libxl__gc *gc, libxl_device_pci *pci,
> - const char *node)
> -{
> - return node ?
> - GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH"/%s",
> - pci->domain, pci->bus, pci->dev, pci->func,
> - node) :
> - GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH,
> - pci->domain, pci->bus, pci->dev, pci->func);
> -}
> -
> -
> -static void pci_info_xs_write(libxl__gc *gc, libxl_device_pci *pci,
> - const char *node, const char *val)
> -{
> - char *path = pci_info_xs_path(gc, pci, node);
> -
> - if ( libxl__xs_printf(gc, XBT_NULL, path, "%s", val) < 0 ) {
> - LOGE(WARN, "Write of %s to node %s failed.", val, path);
> - }
> -}
> -
> -static char *pci_info_xs_read(libxl__gc *gc, libxl_device_pci *pci,
> - const char *node)
> -{
> - char *path = pci_info_xs_path(gc, pci, node);
> -
> - return libxl__xs_read(gc, XBT_NULL, path);
> -}
> -
> -static void pci_info_xs_remove(libxl__gc *gc, libxl_device_pci *pci,
> - const char *node)
> -{
> - char *path = pci_info_xs_path(gc, pci, node);
> - libxl_ctx *ctx = libxl__gc_owner(gc);
> -
> - /* Remove the xenstore entry */
> - xs_rm(ctx->xsh, XBT_NULL, path);
> -}
> -
> static int libxl__device_pci_assignable_add(libxl__gc *gc,
> libxl_device_pci *pci,
> int rebind)
> @@ -1594,6 +1548,9 @@ void libxl__device_pci_add(libxl__egc *egc, uint32_t domid,
> goto out;
> }
>
> + rc = pci_info_xs_write(gc, pci, "domid", GCSPRINTF("%u", domid));
> + if (rc) goto out;
> +
> libxl__device_pci_reset(gc, pci->domain, pci->bus, pci->dev, pci->func);
>
> stubdomid = libxl_get_stubdom_id(ctx, domid);
> @@ -1721,6 +1678,7 @@ static void device_pci_add_done(libxl__egc *egc,
> "PCI device %x:%x:%x.%x (rc %d)",
> pci->domain, pci->bus, pci->dev, pci->func,
> rc);
> + pci_info_xs_remove(gc, pci, "domid");
> }
> aodev->rc = rc;
> aodev->callback(egc, aodev);
> @@ -2282,6 +2240,9 @@ out:
> libxl__xswait_stop(gc, &prs->xswait);
> libxl__ev_time_deregister(gc, &prs->timeout);
> libxl__ev_time_deregister(gc, &prs->retry_timer);
> +
> + if (!rc) pci_info_xs_remove(gc, pci, "domid");
> +
> aodev->rc = rc;
> aodev->callback(egc, aodev);
> }