[Qemu-devel] [PATCH 1/9] Add stub functions for PCI device models to do PCI DMA

[David Gibson <david@gibson.dropbear.id.au>]

This patch adds functions to pci.[ch] to perform PCI DMA operations.  At
present, these are just stubs which perform directly cpu physical memory
accesses.

Using these stubs, however, distinguishes PCI device DMA transactions from
other accesses to physical memory, which will allow PCI IOMMU support to
be added in one place, rather than updating every PCI driver at that time.

That is, it allows us to update individual PCI drivers to support an IOMMU
without having yet determined the details of how the IOMMU emulation will
operate.  This will let us remove the most bitrot-sensitive part of an
IOMMU patch in advance.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 dma.h    |    2 ++
 hw/pci.c |   31 +++++++++++++++++++++++++++++++
 hw/pci.h |   33 +++++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 0 deletions(-)

diff --git a/dma.h b/dma.h
index a6db5ba..06e91cb 100644
--- a/dma.h
+++ b/dma.h
@@ -15,6 +15,8 @@
 #include "hw/hw.h"
 #include "block.h"
 
+typedef target_phys_addr_t dma_addr_t;
+
 typedef struct {
     target_phys_addr_t base;
     target_phys_addr_t len;
diff --git a/hw/pci.c b/hw/pci.c
index 1cdcbb7..0be7611 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -2211,3 +2211,34 @@ MemoryRegion *pci_address_space(PCIDevice *dev)
 {
     return dev->bus->address_space_mem;
 }
+
+#define PCI_DMA_DEFINE_LDST(_lname, _sname, _bits) \
+    uint##_bits##_t ld##_lname##_pci_dma(PCIDevice *dev, dma_addr_t addr) \
+    { \
+        uint##_bits##_t val; \
+        pci_dma_read(dev, addr, &val, sizeof(val)); \
+        return le##_bits##_to_cpu(val); \
+    } \
+    void st##_sname##_pci_dma(PCIDevice *dev, \
+                              dma_addr_t addr, uint##_bits##_t val) \
+    { \
+        val = cpu_to_le##_bits(val); \
+        pci_dma_write(dev, addr, &val, sizeof(val)); \
+    }
+
+uint8_t ldub_pci_dma(PCIDevice *dev, dma_addr_t addr)
+{
+    uint8_t val;
+
+    pci_dma_read(dev, addr, &val, sizeof(val));
+    return val;
+}
+
+void stb_pci_dma(PCIDevice *dev, dma_addr_t addr, uint8_t val)
+{
+    pci_dma_write(dev, addr, &val, sizeof(val));
+}
+
+PCI_DMA_DEFINE_LDST(uw, w, 16);
+PCI_DMA_DEFINE_LDST(l, l, 32);
+PCI_DMA_DEFINE_LDST(q, q, 64);
diff --git a/hw/pci.h b/hw/pci.h
index 391217e..4426e9d 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -6,6 +6,7 @@
 
 #include "qdev.h"
 #include "memory.h"
+#include "dma.h"
 
 /* PCI includes legacy ISA access.  */
 #include "isa.h"
@@ -492,4 +493,36 @@ static inline uint32_t pci_config_size(const PCIDevice *d)
     return pci_is_express(d) ? PCIE_CONFIG_SPACE_SIZE : PCI_CONFIG_SPACE_SIZE;
 }
 
+/* DMA access functions */
+static inline int pci_dma_rw(PCIDevice *dev, dma_addr_t addr,
+                             void *buf, dma_addr_t len, int is_write)
+{
+    cpu_physical_memory_rw(addr, buf, len, is_write);
+    return 0;
+}
+
+static inline int pci_dma_read(PCIDevice *dev, dma_addr_t addr,
+                               void *buf, dma_addr_t len)
+{
+    return pci_dma_rw(dev, addr, buf, len, 0);
+}
+
+static inline int pci_dma_write(PCIDevice *dev, dma_addr_t addr,
+                                const void *buf, dma_addr_t len)
+{
+    return pci_dma_rw(dev, addr, (void *) buf, len, 1);
+}
+
+#define PCI_DMA_DECLARE_LDST(_lname, _sname, _bits) \
+    uint##_bits##_t ld##_lname##_pci_dma(PCIDevice *dev, dma_addr_t addr); \
+    void st##_sname##_pci_dma(PCIDevice *dev, dma_addr_t addr, \
+                              uint##_bits##_t val);            \
+
+PCI_DMA_DECLARE_LDST(ub, b, 8);
+PCI_DMA_DECLARE_LDST(uw, w, 16);
+PCI_DMA_DECLARE_LDST(l, l, 32);
+PCI_DMA_DECLARE_LDST(q, q, 64);
+
+#undef DECLARE_LDST_DMA
+
 #endif
-- 
1.7.5.4