ns16550: enable use of PCI MSI

Which, on x86, requires fiddling with the INTx bit in PCI config space,
since for internally used MSI we can't delegate this to Dom0.

ns16550_init_postirq() also needs (benign) re-ordering of its
operations.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index 764f33a3cab89b3d2ca53eaf4e8519c74a3a0dc7..6f671d32191025f0de14b5708c6510619a66b44a 100644 (file)
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -278,7 +278,7 @@ Flag to indicate whether to probe for a CMOS Real Time Clock irrespective of
 ACPI indicating none to be there.
 
 ### com1,com2
-> `= <baud>[/<base-baud>][,[DPS][,[<io-base>|pci|amt][,[<irq>][,[<port-bdf>][,[<bridge-bdf>]]]]]]`
+> `= <baud>[/<base-baud>][,[DPS][,[<io-base>|pci|amt][,[<irq>|msi][,[<port-bdf>][,[<bridge-bdf>]]]]]]`
 
 Both option `com1` and `com2` follow the same format.
 
@@ -299,7 +299,7 @@ Both option `com1` and `com2` follow the same format.
 * `<io-base>` is an integer which specifies the IO base port for UART
   registers.
 * `<irq>` is the IRQ number to use, or `0` to use the UART in poll
-  mode only.
+  mode only, or `msi` to set up a Message Signaled Interrupt.
 * `<port-bdf>` is the PCI location of the UART, in
   `<bus>:<device>.<function>` notation.
 * `<bridge-bdf>` is the PCI bridge behind which is the UART, in

diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index 5567990fbd01218b79ebd4ef4e5fd31dd25b75e7..babc4147c4cec9c9f8a66ef1815b407369fabaae 100644 (file)
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -742,6 +742,16 @@ static int msi_capability_init(struct pci_dev *dev,
 
     *desc = entry;
     /* Restore the original MSI enabled bits  */
+    if ( !hardware_domain )
+    {
+        /*
+         * ..., except for internal requests (before Dom0 starts), in which
+         * case we rather need to behave "normally", i.e. not follow the split
+         * brain model where Dom0 actually enables MSI (and disables INTx).
+         */
+        pci_intx(dev, false);
+        control |= PCI_MSI_FLAGS_ENABLE;
+    }
     pci_conf_write16(seg, bus, slot, func, msi_control_reg(pos), control);
 
     return 0;
@@ -1019,6 +1029,18 @@ static int msix_capability_init(struct pci_dev *dev,
     ++msix->used_entries;
 
     /* Restore MSI-X enabled bits */
+    if ( !hardware_domain )
+    {
+        /*
+         * ..., except for internal requests (before Dom0 starts), in which
+         * case we rather need to behave "normally", i.e. not follow the split
+         * brain model where Dom0 actually enables MSI (and disables INTx).
+         */
+        pci_intx(dev, false);
+        control |= PCI_MSIX_FLAGS_ENABLE;
+        control &= ~PCI_MSIX_FLAGS_MASKALL;
+        maskall = 0;
+    }
     msix->host_maskall = maskall;
     pci_conf_write16(seg, bus, slot, func, msix_control_reg(pos), control);
 
@@ -1073,6 +1095,8 @@ static void __pci_disable_msi(struct msi_desc *entry)
 
     dev = entry->dev;
     msi_set_enable(dev, 0);
+    if ( entry->irq > 0 && !(irq_to_desc(entry->irq)->status & IRQ_GUEST) )
+        pci_intx(dev, true);
 
     BUG_ON(list_empty(&dev->msi_list));
 }

diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index 3eba56eadcbaf47a60d40d421027d9ceb4655be3..189e121b7e4d0c8ff25d192d488f405f39a061e3 100644 (file)
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -92,6 +92,7 @@ static struct ns16550 {
     u32 bar64;
     u16 cr;
     u8 bar_idx;
+    bool msi;
     const struct ns16550_config_param *param; /* Points into .init.*! */
 #endif
 } ns16550_com[2] = { { 0 } };
@@ -712,6 +713,16 @@ static void __init ns16550_init_preirq(struct serial_port *port)
         uart->fifo_size = 16;
 }
 
+static void __init ns16550_init_irq(struct serial_port *port)
+{
+#ifdef CONFIG_HAS_PCI
+    struct ns16550 *uart = port->uart;
+
+    if ( uart->msi )
+        uart->irq = create_irq(0);
+#endif
+}
+
 static void ns16550_setup_postirq(struct ns16550 *uart)
 {
     if ( uart->irq > 0 )
@@ -746,17 +757,6 @@ static void __init ns16550_init_postirq(struct serial_port *port)
     uart->timeout_ms = max_t(
         unsigned int, 1, (bits * uart->fifo_size * 1000) / uart->baud);
 
-    if ( uart->irq > 0 )
-    {
-        uart->irqaction.handler = ns16550_interrupt;
-        uart->irqaction.name    = "ns16550";
-        uart->irqaction.dev_id  = port;
-        if ( (rc = setup_irq(uart->irq, 0, &uart->irqaction)) != 0 )
-            printk("ERROR: Failed to allocate ns16550 IRQ %d\n", uart->irq);
-    }
-
-    ns16550_setup_postirq(uart);
-
 #ifdef CONFIG_HAS_PCI
     if ( uart->bar || uart->ps_bdf_enable )
     {
@@ -777,8 +777,65 @@ static void __init ns16550_init_postirq(struct serial_port *port)
                                     uart->ps_bdf[0], uart->ps_bdf[1],
                                     uart->ps_bdf[2]);
         }
+
+        if ( uart->msi )
+        {
+            struct msi_info msi = {
+                .bus = uart->ps_bdf[0],
+                .devfn = PCI_DEVFN(uart->ps_bdf[1], uart->ps_bdf[2]),
+                .irq = rc = uart->irq,
+                .entry_nr = 1
+            };
+
+            if ( rc > 0 )
+            {
+                struct msi_desc *msi_desc = NULL;
+
+                pcidevs_lock();
+
+                rc = pci_enable_msi(&msi, &msi_desc);
+                if ( !rc )
+                {
+                    struct irq_desc *desc = irq_to_desc(msi.irq);
+                    unsigned long flags;
+
+                    spin_lock_irqsave(&desc->lock, flags);
+                    rc = setup_msi_irq(desc, msi_desc);
+                    spin_unlock_irqrestore(&desc->lock, flags);
+                    if ( rc )
+                        pci_disable_msi(msi_desc);
+                }
+
+                pcidevs_unlock();
+
+                if ( rc )
+                {
+                    uart->irq = 0;
+                    if ( msi_desc )
+                        msi_free_irq(msi_desc);
+                    else
+                        destroy_irq(msi.irq);
+                }
+            }
+
+            if ( rc )
+                printk(XENLOG_WARNING
+                       "MSI setup failed (%d) for %02x:%02x.%o\n",
+                       rc, uart->ps_bdf[0], uart->ps_bdf[1], uart->ps_bdf[2]);
+        }
     }
 #endif
+
+    if ( uart->irq > 0 )
+    {
+        uart->irqaction.handler = ns16550_interrupt;
+        uart->irqaction.name    = "ns16550";
+        uart->irqaction.dev_id  = port;
+        if ( (rc = setup_irq(uart->irq, 0, &uart->irqaction)) != 0 )
+            printk("ERROR: Failed to allocate ns16550 IRQ %d\n", uart->irq);
+    }
+
+    ns16550_setup_postirq(uart);
 }
 
 static void ns16550_suspend(struct serial_port *port)
@@ -908,6 +965,7 @@ static const struct vuart_info *ns16550_vuart_info(struct serial_port *port)
 
 static struct uart_driver __read_mostly ns16550_driver = {
     .init_preirq  = ns16550_init_preirq,
+    .init_irq     = ns16550_init_irq,
     .init_postirq = ns16550_init_postirq,
     .endboot      = ns16550_endboot,
     .suspend      = ns16550_suspend,
@@ -1261,7 +1319,18 @@ static bool __init parse_positional(struct ns16550 *uart, char **str)
     }
 
     if ( *conf == ',' && *++conf != ',' )
-        uart->irq = simple_strtol(conf, &conf, 10);
+    {
+#ifdef CONFIG_HAS_PCI
+        if ( strncmp(conf, "msi", 3) == 0 )
+        {
+            conf += 3;
+            uart->msi = true;
+            uart->irq = 0;
+        }
+        else
+#endif
+            uart->irq = simple_strtol(conf, &conf, 10);
+    }
 
 #ifdef CONFIG_HAS_PCI
     if ( *conf == ',' && *++conf != ',' )

diff --git a/xen/drivers/pci/pci.c b/xen/drivers/pci/pci.c
index 13d3309ad4841d7af8c0d8499ef89b38c49e747e..1c808d6632034fa3dbcdcc935a3ba53a500b977d 100644 (file)
--- a/xen/drivers/pci/pci.c
+++ b/xen/drivers/pci/pci.c
@@ -115,6 +115,21 @@ int pci_find_next_ext_capability(int seg, int bus, int devfn, int start, int cap
     return 0;
 }
 
+void pci_intx(const struct pci_dev *pdev, bool enable)
+{
+    uint16_t seg = pdev->seg;
+    uint8_t bus = pdev->bus;
+    uint8_t slot = PCI_SLOT(pdev->devfn);
+    uint8_t func = PCI_FUNC(pdev->devfn);
+    uint16_t cmd = pci_conf_read16(seg, bus, slot, func, PCI_COMMAND);
+
+    if ( enable )
+        cmd &= ~PCI_COMMAND_INTX_DISABLE;
+    else
+        cmd |= PCI_COMMAND_INTX_DISABLE;
+    pci_conf_write16(seg, bus, slot, func, PCI_COMMAND, cmd);
+}
+
 const char *__init parse_pci(const char *s, unsigned int *seg_p,
                              unsigned int *bus_p, unsigned int *dev_p,
                              unsigned int *func_p)

diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
index a934662713b558a56b672bea02d5e9c8f1beacd6..8b21e8dc8483dc3d107fcd70f5557ac0d9eb3ce0 100644 (file)
--- a/xen/include/xen/pci.h
+++ b/xen/include/xen/pci.h
@@ -200,6 +200,7 @@ unsigned int pci_size_mem_bar(pci_sbdf_t sbdf, unsigned int pos,
                               uint64_t *paddr, uint64_t *psize,
                               unsigned int flags);
 
+void pci_intx(const struct pci_dev *, bool enable);
 bool_t pcie_aer_get_firmware_first(const struct pci_dev *);
 
 struct pirq;