@@ -93,6 +93,9 @@ by selecting the "signature" item using key 0x0000 (FW_CFG_SIGNATURE),
and reading four bytes from the data register. If the fw_cfg device is
present, the four bytes read will contain the characters "QEMU".
+If the DMA interface is available, then reading the DMA Address
+Register returns 0x51454d5520434647 ("QEMU CFG" in big-endian format).
+
=== Revision / feature bitmap (Key 0x0001, FW_CFG_ID) ===
A 32-bit little-endian unsigned int, this item is used to check for enabled
@@ -53,6 +53,8 @@
#define FW_CFG_DMA_CTL_SKIP 0x04
#define FW_CFG_DMA_CTL_SELECT 0x08
+#define FW_CFG_DMA_SIGNATURE 0x51454d5520434647ULL /* "QEMU CFG" */
+
typedef struct FWCfgEntry {
uint32_t len;
uint8_t *data;
@@ -397,6 +399,13 @@ static void fw_cfg_dma_transfer(FWCfgState *s)
trace_fw_cfg_read(s, 0);
}
+static uint64_t fw_cfg_dma_mem_read(void *opaque, hwaddr addr,
+ unsigned size)
+{
+ /* Return a signature value (and handle various read sizes) */
+ return extract64(FW_CFG_DMA_SIGNATURE, (8 - addr - size) * 8, size * 8);
+}
+
static void fw_cfg_dma_mem_write(void *opaque, hwaddr addr,
uint64_t value, unsigned size)
{
@@ -420,8 +429,8 @@ static void fw_cfg_dma_mem_write(void *opaque, hwaddr addr,
static bool fw_cfg_dma_mem_valid(void *opaque, hwaddr addr,
unsigned size, bool is_write)
{
- return is_write && ((size == 4 && (addr == 0 || addr == 4)) ||
- (size == 8 && addr == 0));
+ return !is_write || ((size == 4 && (addr == 0 || addr == 4)) ||
+ (size == 8 && addr == 0));
}
static bool fw_cfg_data_mem_valid(void *opaque, hwaddr addr,
@@ -492,6 +501,7 @@ static const MemoryRegionOps fw_cfg_comb_mem_ops = {
};
static const MemoryRegionOps fw_cfg_dma_mem_ops = {
+ .read = fw_cfg_dma_mem_read,
.write = fw_cfg_dma_mem_write,
.endianness = DEVICE_BIG_ENDIAN,
.valid.accepts = fw_cfg_dma_mem_valid,
Return a static signature ("QEMU CFG") if the guest does a read to the DMA address io register. Signed-off-by: Kevin O'Connor <kevin@koconnor.net> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> --- Gerd/Marc - if you respin the fw_cfg series, I believe this patch will avoid the Windows compile error. Changes since v2: - use /* */ comments instead of C++ comments - Use ULL on 64bit constants Changes since v1: - use extract64() - reword documentation to be more clear --- docs/specs/fw_cfg.txt | 3 +++ hw/nvram/fw_cfg.c | 14 ++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-)