[Qemu-devel] [PATCH 03/14] Add stub functions for PCI device models to do PCI DMA

[David Gibson]

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.  Stubs are included which are analogous to
cpu_physical_memory_{read,write}(), the stX_phys() and ldX_phys()
functions and cpu_physical_memory_{map,unmap}().

In addition, a wrapper around qemu_sglist_init() is provided, which
also takes a PCIDevice *.  It's assumed that _init() is the only
sglist function which will need wrapping, the idea being that once we
have IOMMU support whatever IOMMU context handle the wrapper derives
from the PCI device will be stored within the sglist structure for
later use.

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 <address@hidden>
Signed-off-by: Alexey Kardashevskiy <address@hidden>
---
 hw/pci.h |   67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 67 insertions(+), 0 deletions(-)

diff --git a/hw/pci.h b/hw/pci.h
index 86a81c8..c449a90 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"
@@ -487,4 +488,70 @@ 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, DMADirection dir)
+{
+    cpu_physical_memory_rw(addr, buf, len, dir == DMA_DIRECTION_FROM_DEVICE);
+    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, DMA_DIRECTION_TO_DEVICE);
+}
+
+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, DMA_DIRECTION_FROM_DEVICE);
+}
+
+#define PCI_DMA_DEFINE_LDST(_l, _s, _bits)                              \
+    static inline uint##_bits##_t ld##_l##_pci_dma(PCIDevice *dev,      \
+                                                   dma_addr_t addr)     \
+    {                                                                   \
+        return ld##_l##_phys(addr);                                     \
+    }                                                                   \
+    static inline void st##_s##_pci_dma(PCIDevice *dev,                 \
+                          dma_addr_t addr, uint##_bits##_t val)         \
+    {                                                                   \
+        st##_s##_phys(addr, val);                                       \
+    }
+
+PCI_DMA_DEFINE_LDST(ub, b, 8);
+PCI_DMA_DEFINE_LDST(uw_le, w_le, 16)
+PCI_DMA_DEFINE_LDST(l_le, l_le, 32);
+PCI_DMA_DEFINE_LDST(q_le, q_le, 64);
+PCI_DMA_DEFINE_LDST(uw_be, w_be, 16)
+PCI_DMA_DEFINE_LDST(l_be, l_be, 32);
+PCI_DMA_DEFINE_LDST(q_be, q_be, 64);
+
+#undef PCI_DMA_DEFINE_LDST
+
+static inline void *pci_dma_map(PCIDevice *dev, dma_addr_t addr,
+                                dma_addr_t *plen, DMADirection dir)
+{
+    target_phys_addr_t len = *plen;
+    void *buf;
+
+    buf = cpu_physical_memory_map(addr, &len, dir == 
DMA_DIRECTION_FROM_DEVICE);
+    *plen = len;
+    return buf;
+}
+
+static inline void pci_dma_unmap(PCIDevice *dev, void *buffer, dma_addr_t len,
+                                 DMADirection dir, dma_addr_t access_len)
+{
+    cpu_physical_memory_unmap(buffer, len, dir == DMA_DIRECTION_FROM_DEVICE,
+                              access_len);
+}
+
+static inline void pci_dma_sglist_init(QEMUSGList *qsg, PCIDevice *dev,
+                                       int alloc_hint)
+{
+    qemu_sglist_init(qsg, alloc_hint);
+}
+
 #endif
-- 
1.7.7