xen-pciback: support wild cards in slot specifications

Particularly for hiding sets of SR-IOV devices, specifying them all
individually is rather cumbersome. Therefore, allow function and slot
numbers to be replaced by a wildcard character ('*').

Unfortunately this gets complicated by the in-kernel sscanf()
implementation not being really standard conformant - matching of
plain text tails cannot be checked by the caller (a patch to overcome
this will be sent shortly, and a follow-up patch for simplifying the
code is planned to be sent when that fixed went upstream).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 82 insertions, 7 deletions

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 03342728bf23..20e1c42c1c48 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -897,17 +897,41 @@ static inline int str_to_slot(const char *buf, int *domain, int *bus,
                               int *slot, int *func)
 {
         int err;
+        char wc = '*';
 
         err = sscanf(buf, " %x:%x:%x.%x", domain, bus, slot, func);
-        if (err == 4)
+        switch (err) {
+        case 3:
+                *func = -1;
+                err = sscanf(buf, " %x:%x:%x.%c", domain, bus, slot, &wc);
+                break;
+        case 2:
+                *slot = *func = -1;
+                err = sscanf(buf, " %x:%x:*.%c", domain, bus, &wc);
+                if (err >= 2)
+                        ++err;
+                break;
+        }
+        if (err == 4 && wc == '*')
                 return 0;
         else if (err < 0)
                 return -EINVAL;
 
         /* try again without domain */
         *domain = 0;
+        wc = '*';
         err = sscanf(buf, " %x:%x.%x", bus, slot, func);
-        if (err == 3)
+        switch (err) {
+        case 2:
+                *func = -1;
+                err = sscanf(buf, " %x:%x.%c", bus, slot, &wc);
+                break;
+        case 1:
+                *slot = *func = -1;
+                err = sscanf(buf, " %x:*.%c", bus, &wc) + 1;
+                break;
+        }
+        if (err == 3 && wc == '*')
                 return 0;
 
         return -EINVAL;
@@ -930,6 +954,19 @@ static int pcistub_device_id_add(int domain, int bus, int slot, int func)
 {
         struct pcistub_device_id *pci_dev_id;
         unsigned long flags;
+        int rc = 0;
+
+        if (slot < 0) {
+                for (slot = 0; !rc && slot < 32; ++slot)
+                        rc = pcistub_device_id_add(domain, bus, slot, func);
+                return rc;
+        }
+
+        if (func < 0) {
+                for (func = 0; !rc && func < 8; ++func)
+                        rc = pcistub_device_id_add(domain, bus, slot, func);
+                return rc;
+        }
 
         pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_KERNEL);
         if (!pci_dev_id)
@@ -952,15 +989,15 @@ static int pcistub_device_id_add(int domain, int bus, int slot, int func)
 static int pcistub_device_id_remove(int domain, int bus, int slot, int func)
 {
         struct pcistub_device_id *pci_dev_id, *t;
-        int devfn = PCI_DEVFN(slot, func);
         int err = -ENOENT;
         unsigned long flags;
 
         spin_lock_irqsave(&device_ids_lock, flags);
         list_for_each_entry_safe(pci_dev_id, t, &pcistub_device_ids,
                                  slot_list) {
-                if (pci_dev_id->domain == domain
-                    && pci_dev_id->bus == bus && pci_dev_id->devfn == devfn) {
+                if (pci_dev_id->domain == domain && pci_dev_id->bus == bus
+                    && (slot < 0 || PCI_SLOT(pci_dev_id->devfn) == slot)
+                    && (func < 0 || PCI_FUNC(pci_dev_id->devfn) == func)) {
                         /* Don't break; here because it's possible the same
                          * slot could be in the list more than once
                          */
@@ -1216,6 +1253,10 @@ static ssize_t permissive_add(struct device_driver *drv, const char *buf,
         err = str_to_slot(buf, &domain, &bus, &slot, &func);
         if (err)
                 goto out;
+        if (slot < 0 || func < 0) {
+                err = -EINVAL;
+                goto out;
+        }
         psdev = pcistub_device_find(domain, bus, slot, func);
         if (!psdev) {
                 err = -ENODEV;
@@ -1297,17 +1338,51 @@ static int __init pcistub_init(void)
 
         if (pci_devs_to_hide && *pci_devs_to_hide) {
                 do {
+                        char wc = '*';
+
                         parsed = 0;
 
                         err = sscanf(pci_devs_to_hide + pos,
                                      " (%x:%x:%x.%x) %n",
                                      &domain, &bus, &slot, &func, &parsed);
-                        if (err != 4) {
+                        switch (err) {
+                        case 3:
+                                func = -1;
+                                err = sscanf(pci_devs_to_hide + pos,
+                                             " (%x:%x:%x.%c) %n",
+                                             &domain, &bus, &slot, &wc,
+                                             &parsed);
+                                break;
+                        case 2:
+                                slot = func = -1;
+                                err = sscanf(pci_devs_to_hide + pos,
+                                             " (%x:%x:*.%c) %n",
+                                             &domain, &bus, &wc, &parsed) + 1;
+                                break;
+                        }
+
+                        if (err != 4 || wc != '*') {
                                 domain = 0;
+                                wc = '*';
                                 err = sscanf(pci_devs_to_hide + pos,
                                              " (%x:%x.%x) %n",
                                              &bus, &slot, &func, &parsed);
-                                if (err != 3)
+                                switch (err) {
+                                case 2:
+                                        func = -1;
+                                        err = sscanf(pci_devs_to_hide + pos,
+                                                     " (%x:%x.%c) %n",
+                                                     &bus, &slot, &wc,
+                                                     &parsed);
+                                        break;
+                                case 1:
+                                        slot = func = -1;
+                                        err = sscanf(pci_devs_to_hide + pos,
+                                                     " (%x:*.%c) %n",
+                                                     &bus, &wc, &parsed) + 1;
+                                        break;
+                                }
+                                if (err != 3 || wc != '*')
                                         goto parse_error;
                         }