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i386/xen: Reserve Xen special pages for console, xenstore rings

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Xen has eight frames at 0xfeff8000 for this; we only really need two for
now and KVM puts the identity map at 0xfeffc000, so limit ourselves to
four.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
This commit is contained in:
David Woodhouse 2022-12-27 19:02:23 +00:00
parent b746a77926
commit 8b57d5c523
2 changed files with 19 additions and 0 deletions
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9
include/sysemu/kvm_xen.h
View File

@ -30,4 +30,13 @@ uint16_t kvm_xen_get_gnttab_max_frames(void);
#define kvm_xen_has_cap(cap) (!!(kvm_xen_get_caps() & \
KVM_XEN_HVM_CONFIG_ ## cap))
#define XEN_SPECIAL_AREA_ADDR 0xfeff8000UL
#define XEN_SPECIAL_AREA_SIZE 0x4000UL
#define XEN_SPECIALPAGE_CONSOLE 0
#define XEN_SPECIALPAGE_XENSTORE 1
#define XEN_SPECIAL_PFN(x) ((XEN_SPECIAL_AREA_ADDR >> TARGET_PAGE_BITS) + \
XEN_SPECIALPAGE_##x)
#endif /* QEMU_SYSEMU_KVM_XEN_H */

10
target/i386/kvm/xen-emu.c
View File

@ -23,6 +23,7 @@
#include "hw/pci/msi.h"
#include "hw/i386/apic-msidef.h"
#include "hw/i386/e820_memory_layout.h"
#include "hw/i386/kvm/xen_overlay.h"
#include "hw/i386/kvm/xen_evtchn.h"
#include "hw/i386/kvm/xen_gnttab.h"
@ -169,6 +170,15 @@ int kvm_xen_init(KVMState *s, uint32_t hypercall_msr)
}
s->xen_caps = xen_caps;
/* Tell fw_cfg to notify the BIOS to reserve the range. */
ret = e820_add_entry(XEN_SPECIAL_AREA_ADDR, XEN_SPECIAL_AREA_SIZE,
E820_RESERVED);
if (ret < 0) {
fprintf(stderr, "e820_add_entry() table is full\n");
return ret;
}
return 0;
}