PCI/MSI: Support allocating virtual MSI interrupts

For NTB devices, we want to be able to trigger MSI interrupts
through a memory window. In these cases we may want to use
more interrupts than the NTB PCI device has available in its MSI-X
table.

We allow for this by creating a new 'virtual' interrupt. These
interrupts are allocated as usual but are not programmed into the
MSI-X table (as there may not be space for them).

The MSI address and data will then handled through an NTB MSI library
introduced later in this series.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index e039b740fe743d5f25421f9ca4982f725566399d..ace978deaf9348cc7239672f264eee0d182afeab 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -192,6 +192,9 @@ static void msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
 
 static void __iomem *pci_msix_desc_addr(struct msi_desc *desc)
 {
+       if (desc->msi_attrib.is_virtual)
+               return NULL;
+
        return desc->mask_base +
                desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
 }
@@ -206,14 +209,19 @@ static void __iomem *pci_msix_desc_addr(struct msi_desc *desc)
 u32 __pci_msix_desc_mask_irq(struct msi_desc *desc, u32 flag)
 {
        u32 mask_bits = desc->masked;
+       void __iomem *desc_addr;
 
        if (pci_msi_ignore_mask)
                return 0;
+       desc_addr = pci_msix_desc_addr(desc);
+       if (!desc_addr)
+               return 0;
 
        mask_bits &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
        if (flag)
                mask_bits |= PCI_MSIX_ENTRY_CTRL_MASKBIT;
-       writel(mask_bits, pci_msix_desc_addr(desc) + PCI_MSIX_ENTRY_VECTOR_CTRL);
+
+       writel(mask_bits, desc_addr + PCI_MSIX_ENTRY_VECTOR_CTRL);
 
        return mask_bits;
 }
@@ -273,6 +281,11 @@ void __pci_read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
        if (entry->msi_attrib.is_msix) {
                void __iomem *base = pci_msix_desc_addr(entry);
 
+               if (!base) {
+                       WARN_ON(1);
+                       return;
+               }
+
                msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR);
                msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR);
                msg->data = readl(base + PCI_MSIX_ENTRY_DATA);
@@ -303,6 +316,9 @@ void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
        } else if (entry->msi_attrib.is_msix) {
                void __iomem *base = pci_msix_desc_addr(entry);
 
+               if (!base)
+                       goto skip;
+
                writel(msg->address_lo, base + PCI_MSIX_ENTRY_LOWER_ADDR);
                writel(msg->address_hi, base + PCI_MSIX_ENTRY_UPPER_ADDR);
                writel(msg->data, base + PCI_MSIX_ENTRY_DATA);
@@ -327,7 +343,13 @@ void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
                                              msg->data);
                }
        }
+
+skip:
        entry->msg = *msg;
+
+       if (entry->write_msi_msg)
+               entry->write_msi_msg(entry, entry->write_msi_msg_data);
+
 }
 
 void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg)
@@ -550,6 +572,7 @@ msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
 
        entry->msi_attrib.is_msix       = 0;
        entry->msi_attrib.is_64         = !!(control & PCI_MSI_FLAGS_64BIT);
+       entry->msi_attrib.is_virtual    = 0;
        entry->msi_attrib.entry_nr      = 0;
        entry->msi_attrib.maskbit       = !!(control & PCI_MSI_FLAGS_MASKBIT);
        entry->msi_attrib.default_irq   = dev->irq;     /* Save IOAPIC IRQ */
@@ -674,6 +697,7 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
        struct irq_affinity_desc *curmsk, *masks = NULL;
        struct msi_desc *entry;
        int ret, i;
+       int vec_count = pci_msix_vec_count(dev);
 
        if (affd)
                masks = irq_create_affinity_masks(nvec, affd);
@@ -696,6 +720,10 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
                        entry->msi_attrib.entry_nr = entries[i].entry;
                else
                        entry->msi_attrib.entry_nr = i;
+
+               entry->msi_attrib.is_virtual =
+                       entry->msi_attrib.entry_nr >= vec_count;
+
                entry->msi_attrib.default_irq   = dev->irq;
                entry->mask_base                = base;
 
@@ -714,12 +742,19 @@ static void msix_program_entries(struct pci_dev *dev,
 {
        struct msi_desc *entry;
        int i = 0;
+       void __iomem *desc_addr;
 
        for_each_pci_msi_entry(entry, dev) {
                if (entries)
                        entries[i++].vector = entry->irq;
-               entry->masked = readl(pci_msix_desc_addr(entry) +
-                               PCI_MSIX_ENTRY_VECTOR_CTRL);
+
+               desc_addr = pci_msix_desc_addr(entry);
+               if (desc_addr)
+                       entry->masked = readl(desc_addr +
+                                             PCI_MSIX_ENTRY_VECTOR_CTRL);
+               else
+                       entry->masked = 0;
+
                msix_mask_irq(entry, 1);
        }
 }
@@ -932,7 +967,7 @@ int pci_msix_vec_count(struct pci_dev *dev)
 EXPORT_SYMBOL(pci_msix_vec_count);
 
 static int __pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
-                            int nvec, struct irq_affinity *affd)
+                            int nvec, struct irq_affinity *affd, int flags)
 {
        int nr_entries;
        int i, j;
@@ -943,7 +978,7 @@ static int __pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
        nr_entries = pci_msix_vec_count(dev);
        if (nr_entries < 0)
                return nr_entries;
-       if (nvec > nr_entries)
+       if (nvec > nr_entries && !(flags & PCI_IRQ_VIRTUAL))
                return nr_entries;
 
        if (entries) {
@@ -1079,7 +1114,8 @@ EXPORT_SYMBOL(pci_enable_msi);
 
 static int __pci_enable_msix_range(struct pci_dev *dev,
                                   struct msix_entry *entries, int minvec,
-                                  int maxvec, struct irq_affinity *affd)
+                                  int maxvec, struct irq_affinity *affd,
+                                  int flags)
 {
        int rc, nvec = maxvec;
 
@@ -1096,7 +1132,7 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
                                return -ENOSPC;
                }
 
-               rc = __pci_enable_msix(dev, entries, nvec, affd);
+               rc = __pci_enable_msix(dev, entries, nvec, affd, flags);
                if (rc == 0)
                        return nvec;
 
@@ -1127,7 +1163,7 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
 int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
                int minvec, int maxvec)
 {
-       return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL);
+       return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
 }
 EXPORT_SYMBOL(pci_enable_msix_range);
 
@@ -1167,7 +1203,7 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
 
        if (flags & PCI_IRQ_MSIX) {
                msix_vecs = __pci_enable_msix_range(dev, NULL, min_vecs,
-                                                   max_vecs, affd);
+                                                   max_vecs, affd, flags);
                if (msix_vecs > 0)
                        return msix_vecs;
        }

diff --git a/include/linux/msi.h b/include/linux/msi.h
index d48e919d55ae71970eb53459ddc1bb580a2fcd44..8ad679e9d9c04a79d0231c92bcc68582ade57cfd 100644 (file)
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -64,6 +64,10 @@ struct ti_sci_inta_msi_desc {
  * @msg:       The last set MSI message cached for reuse
  * @affinity:  Optional pointer to a cpu affinity mask for this descriptor
  *
+ * @write_msi_msg:     Callback that may be called when the MSI message
+ *                     address or data changes
+ * @write_msi_msg_data:        Data parameter for the callback.
+ *
  * @masked:    [PCI MSI/X] Mask bits
  * @is_msix:   [PCI MSI/X] True if MSI-X
  * @multiple:  [PCI MSI/X] log2 num of messages allocated
@@ -90,6 +94,9 @@ struct msi_desc {
        const void                      *iommu_cookie;
 #endif
 
+       void (*write_msi_msg)(struct msi_desc *entry, void *data);
+       void *write_msi_msg_data;
+
        union {
                /* PCI MSI/X specific data */
                struct {
@@ -100,6 +107,7 @@ struct msi_desc {
                                u8      multi_cap       : 3;
                                u8      maskbit         : 1;
                                u8      is_64           : 1;
+                               u8      is_virtual      : 1;
                                u16     entry_nr;
                                unsigned default_irq;
                        } msi_attrib;

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 4a5a84d7bdd43edad868dc8247b8995ca478dec9..19b5c27c6f63be25b32aa9351becde484686d03e 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1362,6 +1362,15 @@ int pci_set_vga_state(struct pci_dev *pdev, bool decode,
 #define PCI_IRQ_MSI            (1 << 1) /* Allow MSI interrupts */
 #define PCI_IRQ_MSIX           (1 << 2) /* Allow MSI-X interrupts */
 #define PCI_IRQ_AFFINITY       (1 << 3) /* Auto-assign affinity */
+
+/*
+ * Virtual interrupts allow for more interrupts to be allocated
+ * than the device has interrupts for. These are not programmed
+ * into the device's MSI-X table and must be handled by some
+ * other driver means.
+ */
+#define PCI_IRQ_VIRTUAL                (1 << 4)
+
 #define PCI_IRQ_ALL_TYPES \
        (PCI_IRQ_LEGACY | PCI_IRQ_MSI | PCI_IRQ_MSIX)