On 02/09/17 09:17, Laszlo Ersek wrote:
Ben,
On 02/05/17 18:09, ben@skyportsystems.com wrote:
From: Ben Warren ben@skyportsystems.com
This command is similar to ADD_POINTER, but instead of patching memory, it writes the pointer back to QEMU over the DMA interface.
Signed-off-by: Ben Warren ben@skyportsystems.com
src/fw/romfile_loader.c | 37 +++++++++++++++++++++++++++++++++++++ src/fw/romfile_loader.h | 16 ++++++++++------ 2 files changed, 47 insertions(+), 6 deletions(-)
while working on the OVMF patches for WRITE_POINTER, something else occurred to me.
As I mentioned in the QEMU thread,
https://www.mail-archive.com/qemu-devel@nongnu.org/msg428495.html
the VMGENID device (or more generally, each device that produces WRITE_POINTER command(s)) should have a reset handler that makes the device forget the GPA(s) that the firmware communicated to it, via WRITE_POINTER. This is because after system reset, all earlier GPAs become meaningless.
What I want to mention here is the corollary to the above. ACPI S3 resume is basically a reset, but the GPAs remain valid, because system memory is preserved. Therefore, at S3 resume, the guest firmware has to replay all the WRITE_POINTER commands. The QEMU reset handler will forcibly forget about the GPAs (which is correct), so the firmware has to re-store them.
... By that I don't necessarily mean to re-run the exact same linker-loader logic; it should be okay to save the *results* of those operations in a simpler array (that is, write exactly what values to what fw_cfg files at what offsets).
And, you can detect whether this is needed at all, the "etc/system-states" fw_cfg file can be used to see if ACPI S3 is enabled or disabled in QEMU. (Please grep QEMU for "disable_s3" and "etc/system-states".)
Thanks Laszlo
I think it can be a separate patch for SeaBIOS (but preferably in this series). I plan to do this in OVMF as well.
Thanks! Laszlo
diff --git a/src/fw/romfile_loader.c b/src/fw/romfile_loader.c index f4b17ff..d0ae42b 100644 --- a/src/fw/romfile_loader.c +++ b/src/fw/romfile_loader.c @@ -5,6 +5,7 @@ #include "romfile.h" // struct romfile_s #include "malloc.h" // Zone*, _malloc #include "output.h" // warn_* +#include "paravirt.h" // qemu_cfg_write_file
struct romfile_loader_file { struct romfile_s *file; @@ -98,7 +99,39 @@ static void romfile_loader_add_pointer(struct romfile_loader_entry_s *entry, pointer += (unsigned long)src_file->data; pointer = cpu_to_le64(pointer); memcpy(dest_file->data + offset, &pointer, entry->pointer_size);
- return;
+err:
- warn_internalerror();
+}
+static void romfile_loader_write_pointer(struct romfile_loader_entry_s *entry,
struct romfile_loader_files *files)+{
struct romfile_s *dest_file;
struct romfile_loader_file *src_file;
unsigned offset = le32_to_cpu(entry->pointer_offset);
u64 pointer = 0;
/* Writing back to a file that may not be loaded in RAM */
dest_file = romfile_find(entry->pointer_dest_file);
src_file = romfile_loader_find(entry->pointer_src_file, files);
if (!dest_file || !src_file || !src_file->data ||
offset + entry->pointer_size < offset ||offset + entry->pointer_size > dest_file->size ||entry->pointer_size < 1 || entry->pointer_size > 8 ||entry->pointer_size & (entry->pointer_size - 1)) {goto err;}
pointer = (unsigned long)src_file->data;
pointer = cpu_to_le64(pointer);
/* Only supported on QEMU */
if (qemu_cfg_write_file(&pointer, dest_file, offset,
entry->pointer_size) != entry->pointer_size) {goto err;} return;
err: warn_internalerror(); @@ -161,6 +194,10 @@ int romfile_loader_execute(const char *name) break; case ROMFILE_LOADER_COMMAND_ADD_CHECKSUM: romfile_loader_add_checksum(entry, files);
break;case ROMFILE_LOADER_COMMAND_WRITE_POINTER:romfile_loader_write_pointer(entry, files);break; default: /* Skip commands that we don't recognize. */ break;diff --git a/src/fw/romfile_loader.h b/src/fw/romfile_loader.h index 15eab2a..0c0782c 100644 --- a/src/fw/romfile_loader.h +++ b/src/fw/romfile_loader.h @@ -25,10 +25,13 @@ struct romfile_loader_entry_s { };
/*
* COMMAND_ADD_POINTER - patch the table (originating from* @dest_file) at @pointer_offset, by adding a pointer to the table
* COMMAND_ADD_POINTER &* COMMAND_WRITE_POINTER - patch memory (originating from* @dest_file) at @pointer.offset, by adding a pointer to the memory * originating from @src_file. 1,2,4 or 8 byte unsigned
* addition is used depending on @pointer_size.
* addition is used depending on @pointer.size.* Instead of patching memory, COMMAND_WRITE_POINTER writes the changes* to @dest_file back to the host via DMA */ struct { char pointer_dest_file[ROMFILE_LOADER_FILESZ];@@ -57,9 +60,10 @@ struct romfile_loader_entry_s { };
enum {
- ROMFILE_LOADER_COMMAND_ALLOCATE = 0x1,
- ROMFILE_LOADER_COMMAND_ADD_POINTER = 0x2,
- ROMFILE_LOADER_COMMAND_ADD_CHECKSUM = 0x3,
- ROMFILE_LOADER_COMMAND_ALLOCATE = 0x1,
- ROMFILE_LOADER_COMMAND_ADD_POINTER = 0x2,
- ROMFILE_LOADER_COMMAND_ADD_CHECKSUM = 0x3,
- ROMFILE_LOADER_COMMAND_WRITE_POINTER = 0x4,
};
enum {