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hw/xen: Implement soft reset for emulated gnttab

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This is only part of it; we will also need to get the PV back end drivers
to tear down their own mappings (or do it for them, but they kind of need
to stop using the pointers too).

Some more work on the actual PV back ends and xen-bus code is going to be
needed to really make soft reset and migration fully functional, and this
part is the basis for that.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
This commit is contained in:
David Woodhouse 2023-01-10 01:09:04 +00:00
parent d05864d23b
commit de26b26197
3 changed files with 30 additions and 2 deletions
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26
hw/i386/kvm/xen_gnttab.c
View File

@ -72,13 +72,11 @@ static void xen_gnttab_realize(DeviceState *dev, Error **errp)
error_setg(errp, "Xen grant table support is for Xen emulation");
return;
}
s->nr_frames = 0;
s->max_frames = kvm_xen_get_gnttab_max_frames();
memory_region_init_ram(&s->gnt_frames, OBJECT(dev), "xen:grant_table",
XEN_PAGE_SIZE * s->max_frames, &error_abort);
memory_region_set_enabled(&s->gnt_frames, true);
s->entries.v1 = memory_region_get_ram_ptr(&s->gnt_frames);
memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
/* Create individual page-sizes aliases for overlays */
s->gnt_aliases = (void *)g_new0(MemoryRegion, s->max_frames);
@ -90,8 +88,11 @@ static void xen_gnttab_realize(DeviceState *dev, Error **errp)
s->gnt_frame_gpas[i] = INVALID_GPA;
}
s->nr_frames = 0;
memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
s->entries.v1[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access;
s->entries.v1[GNTTAB_RESERVED_XENSTORE].frame = XEN_SPECIAL_PFN(XENSTORE);
qemu_mutex_init(&s->gnt_lock);
xen_gnttab_singleton = s;
@ -523,3 +524,24 @@ static struct gnttab_backend_ops emu_gnttab_backend_ops = {
.unmap = xen_be_gnttab_unmap,
};
int xen_gnttab_reset(void)
{
XenGnttabState *s = xen_gnttab_singleton;
if (!s) {
return -ENOTSUP;
}
QEMU_LOCK_GUARD(&s->gnt_lock);
s->nr_frames = 0;
memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
s->entries.v1[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access;
s->entries.v1[GNTTAB_RESERVED_XENSTORE].frame = XEN_SPECIAL_PFN(XENSTORE);
memset(s->map_track, 0, s->max_frames * ENTRIES_PER_FRAME_V1);
return 0;
}

1
hw/i386/kvm/xen_gnttab.h
View File

@ -13,6 +13,7 @@
#define QEMU_XEN_GNTTAB_H
void xen_gnttab_create(void);
int xen_gnttab_reset(void);
int xen_gnttab_map_page(uint64_t idx, uint64_t gfn);
struct gnttab_set_version;

5
target/i386/kvm/xen-emu.c
View File

@ -1406,6 +1406,11 @@ int kvm_xen_soft_reset(void)
return err;
}
err = xen_gnttab_reset();
if (err) {
return err;
}
err = xen_xenstore_reset();
if (err) {
return err;