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[Qemu-devel] Re: [PATCH 3/5] replace cpu_physical_memory_rw


From: Anthony Liguori
Subject: [Qemu-devel] Re: [PATCH 3/5] replace cpu_physical_memory_rw
Date: Wed, 17 Dec 2008 14:56:05 -0600
User-agent: Thunderbird 2.0.0.17 (X11/20080925)

Glauber Costa wrote:
This patch introduces a kvm version of cpu_physical_memory_rw.
The main motivation is to bypass tcg version, which contains
tcg-specific code, as well as data structures not used by kvm,
such as l1_phys_map.

In this patch, I'm using a runtime selection of which function
to call, but the mid-term goal is to use function pointers in
a way very close to which QEMUAccel used to be.

Signed-off-by: Glauber Costa <address@hidden>
---
 exec.c    |   13 +++++++++++--
 kvm-all.c |   39 +++++++++++++++++++++++++++++++++++----
 kvm.h     |    2 ++
 3 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/exec.c b/exec.c
index 04eadfe..d5c88b1 100644
--- a/exec.c
+++ b/exec.c
@@ -2938,8 +2938,8 @@ int cpu_physical_memory_do_io(target_phys_addr_t addr, 
uint8_t *buf, int l, int

+
+void kvm_cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
+                                int len, int is_write)
+{
+    KVMSlot *mem;
+    KVMState *s = kvm_state;
+    int l;
+
+    mem = kvm_lookup_slot(s, addr);
+    if (!mem)
+        return;
+
+    if ((mem->phys_offset & ~TARGET_PAGE_MASK) >= TLB_MMIO) {
+        l = 0;
+        while (len > l)
+            l += cpu_physical_memory_do_io(addr + l, buf + l, len - l, is_write, 
mem->phys_offset);
+    } else {
+        uint8_t *uaddr = phys_ram_base + mem->phys_offset + (addr - 
mem->start_addr);
+        if (!is_write)
+            memcpy(buf, uaddr, len);
+        else
+            memcpy(uaddr, buf, len);
+    }
+}

I think this is a bit optimistic. It assumes addr..len fits entirely within a slot. That's not necessarily the case though. I think you should probably limit len to whatever is left in the slot, then if necessary, (tail) recursively call kvm_cpu_physical_memory_rw.

Regards,

Anthony Liguori




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