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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: [PATCH 6 of 6] xl: implement multifunction device PCI pass-through
On Wed, 2010-08-04 at 15:52 +0100, Stefano Stabellini wrote:
> On Mon, 2 Aug 2010, Gianni Tedesco (3P) wrote:
> > tools/libxl/libxl.h | 1 +
> > tools/libxl/libxl_pci.c | 118
> > ++++++++++++++++++++++++++++++++++++++++++++---
> > 2 files changed, 111 insertions(+), 8 deletions(-)
> >
> >
> > # HG changeset patch
> > # User Gianni Tedesco <gianni.tedesco@xxxxxxxxxx>
> > # Date 1280760698 -3600
> > # Branch pci-patches-v3
> > # Node ID 6379343447e58cc7b83e27beba9c35e62c232d9d
> > # Parent eb8ee481bc063b18b39feaa76d9b757331ed3a9f
> > xl: implement multifunction device PCI pass-through
> >
> > Implement PCI pass-through for multi-function devices. The supported BDF
> > notation is: BB:DD.* - therefore passing-through a subset of functions or
> > remapping the function numbers is not supported. Largely because I don't see
> > how that can ever be safe or sane (perhaps for SR-IOV cards?)
> >
> > Letting qemu automatically select the virtual slot is not supported since I
> > don't believe that qemu-dm can actually handle that case.
> >
> > Signed-off-by: Gianni Tedesco <gianni.tedesco@xxxxxxxxxx>
> >
> > diff -r eb8ee481bc06 -r 6379343447e5 tools/libxl/libxl.h
> > --- a/tools/libxl/libxl.h Mon Aug 02 15:47:38 2010 +0100
> > +++ b/tools/libxl/libxl.h Mon Aug 02 15:51:38 2010 +0100
> > @@ -308,6 +308,7 @@ typedef struct {
> > unsigned int vdevfn;
> > bool msitranslate;
> > bool power_mgmt;
> > + bool multifunction;
> > } libxl_device_pci;
> >
> > enum {
> > diff -r eb8ee481bc06 -r 6379343447e5 tools/libxl/libxl_pci.c
> > --- a/tools/libxl/libxl_pci.c Mon Aug 02 15:47:38 2010 +0100
> > +++ b/tools/libxl/libxl_pci.c Mon Aug 02 15:51:38 2010 +0100
> > @@ -136,8 +136,13 @@ int libxl_device_pci_parse_bdf(libxl_ctx
> > break;
> > }
> > *ptr = '\0';
> > - if ( hex_convert(tok, &func, 0x7) )
> > - goto parse_error;
> > + if ( !strcmp(tok, "*") ) {
> > + pcidev->multifunction = 1;
> > + }else{
> > + if ( hex_convert(tok, &func, 0x7) )
> > + goto parse_error;
> > + pcidev->multifunction = 0;
> > + }
> > tok = ptr + 1;
> > }
> > break;
>
> Couldn't you add the func_mask somewhere in libxl_device_pci, instead of
> calling pci_multifunction_check multilple times?
> Would be possible to make the normal passthrough case just a subset of
> the general multifunction passthrough case to simplify the code?
Not sure what you mean by this, the parsing parts don't (and oughtn't)
frob about with sysfs nodes etc. The pci_multifunction_check function is
called once per device add and once per device remove iff the parser had
seen XX:YY.* notation indicating multifunction devices.
>
> > @@ -531,6 +536,50 @@ int libxl_device_pci_list_assignable(lib
> > return 0;
> > }
> >
> > +static int pci_multifunction_check(libxl_ctx *ctx, libxl_device_pci
> > *pcidev, unsigned int *func_mask)
> > +{
>
> a comment on top of this function to explain what it is actually checking
> would be nice
This function checks that all functions of a device are bound to pciback
driver. It also initialises a bit-mask of which function numbers are
present on that device.
I shall add the comment in next rev.
> > + struct dirent *de;
> > + DIR *dir;
> > +
> > + *func_mask = 0;
> > +
> > + dir = opendir(SYSFS_PCI_DEV);
> > + if ( NULL == dir ) {
> > + XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "Couldn't open %s", SYSFS_PCI_DEV);
> > + return -1;
> > + }
> > +
> > + while( (de = readdir(dir)) ) {
> > + unsigned dom, bus, dev, func;
> > + struct stat st;
> > + char *path;
> > +
> > + if ( sscanf(de->d_name, PCI_BDF, &dom, &bus, &dev, &func) != 4 )
> > + continue;
> > + if ( pcidev->domain != dom )
> > + continue;
> > + if ( pcidev->bus != bus )
> > + continue;
> > + if ( pcidev->dev != dev )
> > + continue;
> > +
> > + path = libxl_sprintf(ctx, "%s/" PCI_BDF, SYSFS_PCIBACK_DRIVER,
> > dom, bus, dev, func);
> > + if ( lstat(path, &st) ) {
> > + if ( errno == ENOENT )
> > + XL_LOG(ctx, XL_LOG_ERROR, PCI_BDF " is not assigned to
> > pciback driver",
> > + dom, bus, dev, func);
> > + else
> > + XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "Couldn't lstat %s", path);
> > + closedir(dir);
> > + return -1;
> > + }
> > + (*func_mask) |= (1 << func);
> > + }
> > +
> > + closedir(dir);
> > + return 0;
> > +}
> > +
> > static int pci_ins_check(libxl_ctx *ctx, uint32_t domid, const char
> > *state, void *priv)
> > {
> > char *orig_state = priv;
> > @@ -679,10 +728,32 @@ int libxl_device_pci_add(libxl_ctx *ctx,
> > return rc;
> > }
> >
> > + if ( pcidev->multifunction ) {
> > + unsigned int i, orig_vdev, func_mask, rc = 0;
> > + orig_vdev = pcidev->vdevfn & ~7U;
> > +
> > + if ( pci_multifunction_check(ctx, pcidev, &func_mask) )
> > + return ERROR_FAIL;
> > + if ( !(pcidev->vdevfn >> 3) ) {
> > + XL_LOG(ctx, XL_LOG_ERROR, "Must specify a v-slot for
> > multi-function devices");
> > + return ERROR_FAIL;
> > + }
> > +
> > + for(i = 7; i < 8; --i) {
>
> shouldn't this be for(i = 7; i >= 0; --i)?
That will generate a compiler warning since unsigned int's are always >=
0. The code relies on an underflow condition. However, I could change it
to int if you think that makes it clearer.
> > + if ( (1 << i) & func_mask ) {
> > + pcidev->func = i;
> > + pcidev->vdevfn = orig_vdev | i;
> > + if ( do_pci_add(ctx, domid, pcidev) )
> > + rc = ERROR_FAIL;
> > + }
> > + }
> > + return rc;
> > + }
> > +
> > return do_pci_add(ctx, domid, pcidev);
> > }
> >
> > -int libxl_device_pci_remove(libxl_ctx *ctx, uint32_t domid,
> > libxl_device_pci *pcidev)
> > +static int do_pci_remove(libxl_ctx *ctx, uint32_t domid, libxl_device_pci
> > *pcidev)
> > {
> > libxl_device_pci *assigned;
> > char *path;
> > @@ -711,10 +782,15 @@ int libxl_device_pci_remove(libxl_ctx *c
> > libxl_xs_write(ctx, XBT_NULL, path, PCI_BDF, pcidev->domain,
> > pcidev->bus, pcidev->dev, pcidev->func);
> > path = libxl_sprintf(ctx,
> > "/local/domain/0/device-model/%d/command", domid);
> > - xs_write(ctx->xsh, XBT_NULL, path, "pci-rem", strlen("pci-rem"));
> > - if (libxl_wait_for_device_model(ctx, domid, "pci-removed", NULL,
> > NULL) < 0) {
> > - XL_LOG(ctx, XL_LOG_ERROR, "Device Model didn't respond in
> > time");
> > - return ERROR_FAIL;
> > +
> > + /* Remove all functions at once atomically by only signalling
> > + * device-model for function 0 */
> > + if ( !pcidev->multifunction || pcidev->func == 0 ) {
> > + xs_write(ctx->xsh, XBT_NULL, path, "pci-rem",
> > strlen("pci-rem"));
> > + if (libxl_wait_for_device_model(ctx, domid, "pci-removed",
> > NULL, NULL) < 0) {
> > + XL_LOG(ctx, XL_LOG_ERROR, "Device Model didn't respond in
> > time");
> > + return ERROR_FAIL;
> > + }
> > }
> > path = libxl_sprintf(ctx, "/local/domain/0/device-model/%d/state",
> > domid);
> > xs_write(ctx->xsh, XBT_NULL, path, state, strlen(state));
> > @@ -769,7 +845,10 @@ skip1:
> > fclose(f);
> > }
> > out:
> > - libxl_device_pci_reset(ctx, pcidev->domain, pcidev->bus, pcidev->dev,
> > pcidev->func);
> > + /* don't do multiple resets while some functions are still passed
> > through */
> > + if ( !pcidev->multifunction || pcidev->func == 0 ) {
> > + libxl_device_pci_reset(ctx, pcidev->domain, pcidev->bus,
> > pcidev->dev, pcidev->func);
> > + }
> >
> > if (!libxl_is_stubdom(ctx, domid, NULL)) {
> > rc = xc_deassign_device(ctx->xch, domid, pcidev->value);
> > @@ -786,6 +865,29 @@ out:
> > return 0;
> > }
> >
> > +int libxl_device_pci_remove(libxl_ctx *ctx, uint32_t domid,
> > libxl_device_pci *pcidev)
> > +{
> > + if ( pcidev->multifunction ) {
> > + unsigned int i, orig_vdev, func_mask, rc;
> > + orig_vdev = pcidev->vdevfn & ~7U;
> > +
> > + if ( pci_multifunction_check(ctx, pcidev, &func_mask) )
> > + return ERROR_FAIL;
> > +
> > + for(i = 7; i < 8; --i) {
>
> same here
>
> > + if ( (1 << i) & func_mask ) {
> > + pcidev->func = i;
> > + pcidev->vdevfn = orig_vdev | i;
> > + if ( do_pci_remove(ctx, domid, pcidev) )
> > + rc = ERROR_FAIL;
> > + }
> > + }
> > + return rc;
> > + }
> > +
> > + return do_pci_remove(ctx, domid, pcidev);
> > +}
> > +
> > int libxl_device_pci_list_assigned(libxl_ctx *ctx, libxl_device_pci
> > **list, uint32_t domid, int *num)
> > {
> > char *be_path, *num_devs, *xsdev, *xsvdevfn, *xsopts;
> >
>
>
> applied all the other patches in the series
OK thanks.
I will also need to handle cleanup in the error path of multifunction
device addition as discussed. This can actually happen quite easily if
function 0 alone is assigned to another domain because
pci_multifunction_check() doesn't look in xenstore and also because of
missing safety checks. Specifically, when adding a non-multifunction
device we need a check to make sure that the physical device really has
only one function.
I am thinking that we probably ought to scrap the XX:YY.* notation and
enforce that function is ALWAYS set to 0. Then when adding/removing the
device we should check for additional functions and handle them
transparently to the user. As I said in the commit message I am unaware
of any valid uses for separating functions but I need to look at how
SR-IOV works.
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