On 3/7/25 08:49, Philippe Mathieu-Daudé wrote:
On 7/3/25 17:38, Alex Bennée wrote:
Philippe Mathieu-Daudé <phi...@linaro.org> writes:
Use qemu_arch_available() to check at runtime if a target
architecture is built in.
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
hw/virtio/virtio-mem.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index 5f57eccbb66..8c40042108c 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -15,6 +15,7 @@
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qemu/units.h"
+#include "system/arch_init.h"
#include "system/numa.h"
#include "system/system.h"
#include "system/reset.h"
@@ -170,13 +171,16 @@ static bool virtio_mem_has_shared_zeropage(RAMBlock *rb)
* necessary (as the section size can change). But it's more likely that the
* section size will rather get smaller and not bigger over time.
*/
-#if defined(TARGET_X86_64) || defined(TARGET_I386) || defined(TARGET_S390X)
-#define VIRTIO_MEM_USABLE_EXTENT (2 * (128 * MiB))
-#elif defined(TARGET_ARM)
-#define VIRTIO_MEM_USABLE_EXTENT (2 * (512 * MiB))
-#else
-#error VIRTIO_MEM_USABLE_EXTENT not defined
-#endif
+static uint64_t virtio_mem_usable_extent_size(void)
+{
+ if (qemu_arch_available(QEMU_ARCH_I386 | QEMU_ARCH_S390X)) {
+ return 2 * 128 * MiB;
+ } else if (qemu_arch_available(QEMU_ARCH_ARM)) {
+ return 2 * 512 * MiB;
+ } else {
+ g_assert_not_reached();
+ }
+}
What happens if/when we have multiple arches available? Won't we want to
know which CPU the virtio-mem device is attached to or do we take the
minimal value over the whole system?
"per attached vcpu" is how I was previously considering this problem,
but IIUC from the discussions with Pierrick, we should consider single
binary as a first step before heterogeneous emulation.
I think it's safe to assume only a single arch is enable for now, in the
context of the single binary.
A thing we could do is introduce qemu_arch_heterogenenous_emulation(),
that returns false for now. And assert this in places that will need to
be changed. So spots that will need refactoring will already be flagged
in the codebase.
Reviewed-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>
If you think the minimal value is good enough, then that'd be my
preferred choice, as the simplest to implement.
static bool virtio_mem_is_busy(void)
{
@@ -721,7 +725,7 @@ static void virtio_mem_resize_usable_region(VirtIOMEM *vmem,
bool can_shrink)
{
uint64_t newsize = MIN(memory_region_size(&vmem->memdev->mr),
- requested_size + VIRTIO_MEM_USABLE_EXTENT);
+ requested_size + virtio_mem_usable_extent_size());
/* The usable region size always has to be multiples of the block size. */
newsize = QEMU_ALIGN_UP(newsize, vmem->block_size);
