msi/msix: added API to set MSI message address and data

Added (msi|msix)_set_message() function for whoever might
want to use them.

Currently msi_notify()/msix_notify() write to these vectors to
signal the guest about an interrupt so the correct values have to
written there by the guest or QEMU.

For example, POWER guest never initializes MSI/MSIX vectors, instead
it uses RTAS hypercalls. So in order to support MSIX for virtio-pci on
POWER we have to initialize MSI/MSIX message from QEMU.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 32 insertions, 0 deletions

diff --git a/hw/msi.c b/hw/msi.c
index 52332041e7..e2273a09ae 100644
--- a/hw/msi.c
+++ b/hw/msi.c
@@ -105,6 +105,23 @@ static inline uint8_t msi_pending_off(const PCIDevice* dev, bool msi64bit)
     return dev->msi_cap + (msi64bit ? PCI_MSI_PENDING_64 : PCI_MSI_PENDING_32);
 }
 
+/*
+ * Special API for POWER to configure the vectors through
+ * a side channel. Should never be used by devices.
+ */
+void msi_set_message(PCIDevice *dev, MSIMessage msg)
+{
+    uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
+    bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
+
+    if (msi64bit) {
+        pci_set_quad(dev->config + msi_address_lo_off(dev), msg.address);
+    } else {
+        pci_set_long(dev->config + msi_address_lo_off(dev), msg.address);
+    }
+    pci_set_word(dev->config + msi_data_off(dev, msi64bit), msg.data);
+}
+
 bool msi_enabled(const PCIDevice *dev)
 {
     return msi_present(dev) &&
diff --git a/hw/msi.h b/hw/msi.h
index 75747abc25..6ec1f99f80 100644
--- a/hw/msi.h
+++ b/hw/msi.h
@@ -31,6 +31,7 @@ struct MSIMessage {
 
 extern bool msi_supported;
 
+void msi_set_message(PCIDevice *dev, MSIMessage msg);
 bool msi_enabled(const PCIDevice *dev);
 int msi_init(struct PCIDevice *dev, uint8_t offset,
              unsigned int nr_vectors, bool msi64bit, bool msi_per_vector_mask);
diff --git a/hw/msix.c b/hw/msix.c
index fd9ea95da1..800fc32f0b 100644
--- a/hw/msix.c
+++ b/hw/msix.c
@@ -37,6 +37,19 @@ static MSIMessage msix_get_message(PCIDevice *dev, unsigned vector)
     return msg;
 }
 
+/*
+ * Special API for POWER to configure the vectors through
+ * a side channel. Should never be used by devices.
+ */
+void msix_set_message(PCIDevice *dev, int vector, struct MSIMessage msg)
+{
+    uint8_t *table_entry = dev->msix_table + vector * PCI_MSIX_ENTRY_SIZE;
+
+    pci_set_quad(table_entry + PCI_MSIX_ENTRY_LOWER_ADDR, msg.address);
+    pci_set_long(table_entry + PCI_MSIX_ENTRY_DATA, msg.data);
+    table_entry[PCI_MSIX_ENTRY_VECTOR_CTRL] &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
+}
+
 static uint8_t msix_pending_mask(int vector)
 {
     return 1 << (vector % 8);
diff --git a/hw/msix.h b/hw/msix.h
index 1786e2766b..15211cb592 100644
--- a/hw/msix.h
+++ b/hw/msix.h
@@ -4,6 +4,7 @@
 #include "qemu-common.h"
 #include "pci.h"
 
+void msix_set_message(PCIDevice *dev, int vector, MSIMessage msg);
 int msix_init(PCIDevice *dev, unsigned short nentries,
               MemoryRegion *table_bar, uint8_t table_bar_nr,
               unsigned table_offset, MemoryRegion *pba_bar,