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[Qemu-devel] [PATCH 2/4] exec: introduce cpu_physical_memory_map_fast an
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 2/4] exec: introduce cpu_physical_memory_map_fast and cpu_physical_memory_map_check |
Date: |
Tue, 3 May 2011 18:49:32 +0200 |
Paravirtualized devices (and also some real devices) can assume they
are going to access RAM. For this reason, provide a fast-path
function with the following properties:
1) it will never allocate a bounce buffer
2) it can be used for read-modify-write operations
3) unlike qemu_get_ram_ptr, it is safe because it recognizes "short" blocks
To use cpu_physical_memory_map_fast for RMW, just pass 1 to is_write
when unmapping.
Signed-off-by: Paolo Bonzini <address@hidden>
---
cpu-common.h | 4 ++++
exec.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+), 0 deletions(-)
diff --git a/cpu-common.h b/cpu-common.h
index 96c02ae..d6e116d 100644
--- a/cpu-common.h
+++ b/cpu-common.h
@@ -80,6 +80,10 @@ static inline void
cpu_physical_memory_write(target_phys_addr_t addr,
void *cpu_physical_memory_map(target_phys_addr_t addr,
target_phys_addr_t *plen,
int is_write);
+void *cpu_physical_memory_map_fast(target_phys_addr_t addr,
+ target_phys_addr_t *plen);
+bool cpu_physical_memory_map_check(target_phys_addr_t addr,
+ target_phys_addr_t len);
void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
int is_write, target_phys_addr_t access_len);
void *cpu_register_map_client(void *opaque, void (*callback)(void *opaque));
diff --git a/exec.c b/exec.c
index 9b2c9e4..2b88c29 100644
--- a/exec.c
+++ b/exec.c
@@ -3944,6 +3944,19 @@ static void
*cpu_physical_memory_map_internal(target_phys_addr_t addr,
/* Map a physical memory region into a host virtual address.
* May map a subset of the requested range, given by and returned in *plen.
+ * May return NULL if extra resources are needed to perform the mapping
+ * (i.e. cpu_physical_memory_map is needed).
+ * It may be used for read-modify-write operations.
+ */
+void *cpu_physical_memory_map_fast(target_phys_addr_t addr,
+ target_phys_addr_t *plen)
+{
+ uintptr_t pd;
+ return cpu_physical_memory_map_internal(addr, plen, &pd);
+}
+
+/* Map a physical memory region into a host virtual address.
+ * May map a subset of the requested range, given by and returned in *plen.
* May return NULL if resources needed to perform the mapping are exhausted.
* Use only for reads OR writes - not for read-modify-write operations.
* Use cpu_register_map_client() to know when retrying the map operation is
@@ -3981,6 +3994,24 @@ void *cpu_physical_memory_map(target_phys_addr_t addr,
return bounce.buffer;
}
+/* Returns true if the entire area between ADDR and ADDR+LEN (inclusive
+ * and exclusive, respectively) can be mapped by cpu_physical_memory_map_fast
+ * (possibly in multiple steps).
+ */
+bool cpu_physical_memory_map_check(target_phys_addr_t addr,
+ target_phys_addr_t len)
+{
+ while (len > 0) {
+ target_phys_addr_t l = len;
+ if (!cpu_physical_memory_map_fast(addr, &l)) {
+ return false;
+ }
+ len -= l;
+ addr += l;
+ }
+ return true;
+}
+
/* Unmaps a memory region previously mapped by cpu_physical_memory_map().
* Will also mark the memory as dirty if is_write == 1. access_len gives
* the amount of memory that was actually read or written by the caller.
--
1.7.4.4
- [Qemu-devel] [PATCH 0/4] introduce cpu_physical_memory_map_fast, Paolo Bonzini, 2011/05/03
- [Qemu-devel] [PATCH 1/4] exec: extract cpu_physical_memory_map_internal, Paolo Bonzini, 2011/05/03
- [Qemu-devel] [PATCH 3/4] virtio: use cpu_physical_memory_map_fast, Paolo Bonzini, 2011/05/03
- [Qemu-devel] [PATCH 4/4] milkymist: use cpu_physical_memory_map_fast, Paolo Bonzini, 2011/05/03
- [Qemu-devel] [PATCH 2/4] exec: introduce cpu_physical_memory_map_fast and cpu_physical_memory_map_check,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/4] introduce cpu_physical_memory_map_fast, Paolo Bonzini, 2011/05/12
- Re: [Qemu-devel] [PATCH 0/4] introduce cpu_physical_memory_map_fast, Avi Kivity, 2011/05/12