[Qemu-devel] [PATCH 2 of 5] add can_dma/post_dma for direct IO

[Andrea Arcangeli <aarcange@redhat.com>]

From: Andrea Arcangeli <aarcange@redhat.com>

Add can_dma and post_dma methods needed before/after direct IO to guest
physical memory.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/cpu-all.h b/cpu-all.h
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -912,6 +912,11 @@ CPUReadMemoryFunc **cpu_get_io_memory_re
 
 void cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
                             size_t len, int is_write);
+void cpu_physical_memory_write_post_dma(target_phys_addr_t addr,
+                                        size_t len);
+uint8_t *cpu_physical_memory_can_dma(target_phys_addr_t addr,
+                                     size_t len, int is_write,
+                                     int alignment);
 static inline void cpu_physical_memory_read(target_phys_addr_t addr,
                                             uint8_t *buf, size_t len)
 {
diff --git a/exec.c b/exec.c
--- a/exec.c
+++ b/exec.c
@@ -2974,6 +2974,111 @@ void cpu_physical_memory_rw(target_phys_
     }
 }
 
+uint8_t *cpu_physical_memory_can_dma(target_phys_addr_t addr,
+                                     size_t len, int is_write,
+                                     int alignment)
+{
+    int l, first = 1;
+    uint8_t *ptr = NULL;
+    target_phys_addr_t page;
+    unsigned long pd, pd_first = 0;
+    PhysPageDesc *p;
+
+    if (len & (alignment-1))
+        goto out;
+
+    while (len > 0) {
+        page = addr & TARGET_PAGE_MASK;
+        p = phys_page_find(page >> TARGET_PAGE_BITS);
+
+        l = (page + TARGET_PAGE_SIZE) - addr;
+        if (l > len)
+            l = len;
+
+        if (!p)
+            pd = IO_MEM_UNASSIGNED;
+        else
+            pd = p->phys_offset;
+
+        if (is_write) {
+            if ((pd & ~TARGET_PAGE_MASK) != IO_MEM_RAM)
+                return NULL;
+        } else {
+            if ((pd & ~TARGET_PAGE_MASK) > IO_MEM_ROM &&
+                !(pd & IO_MEM_ROMD))
+                return NULL;
+        }
+
+        if (first) {
+            first = 0;
+            ptr = phys_ram_base + (pd & TARGET_PAGE_MASK) +
+                (addr & ~TARGET_PAGE_MASK);
+            if ((unsigned long)ptr & (alignment-1))
+                return NULL;
+            pd_first = pd;
+        }
+
+        /* nonlinear range */
+        if (pd_first != pd)
+            return NULL;
+        pd_first += TARGET_PAGE_SIZE;
+
+        len -= l;
+        addr += l;
+    }
+
+out:
+    return ptr;
+}
+
+void cpu_physical_memory_write_post_dma(target_phys_addr_t addr,
+                                        size_t len)
+{
+    int l;
+    uint8_t *ptr;
+    target_phys_addr_t page;
+    unsigned long pd;
+    PhysPageDesc *p;
+
+    while (len > 0) {
+        page = addr & TARGET_PAGE_MASK;
+
+        l = (page + TARGET_PAGE_SIZE) - addr;
+        if (l > len)
+            l = len;
+
+        p = phys_page_find(page >> TARGET_PAGE_BITS);
+        if (!p)
+            pd = IO_MEM_UNASSIGNED;
+        else
+            pd = p->phys_offset;
+
+        if ((pd & ~TARGET_PAGE_MASK) != IO_MEM_RAM) {
+            printf("ERROR cpu_physical_memory_post_dma: memory layout changed\n");
+            continue;
+        } else {
+            unsigned long addr1;
+            addr1 = (pd & TARGET_PAGE_MASK) + (addr & ~TARGET_PAGE_MASK);
+            /* RAM case */
+            ptr = phys_ram_base + addr1;
+            if (!cpu_physical_memory_is_dirty(addr1)) {
+                /* invalidate code */
+                tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
+                /* set dirty bit */
+                phys_ram_dirty[addr1 >> TARGET_PAGE_BITS] |=
+                    (0xff & ~CODE_DIRTY_FLAG);
+            }
+            /* qemu doesn't execute guest code directly, but kvm does
+               therefore fluch instruction caches */
+            if (kvm_enabled())
+                flush_icache_range((unsigned long)ptr,
+                                   ((unsigned long)ptr)+l);
+        }
+        len -= l;
+        addr += l;
+    }
+}
+
 /* used for ROM loading : can write in RAM and ROM */
 void cpu_physical_memory_write_rom(target_phys_addr_t addr,
                                    const uint8_t *buf, int len)