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kvm: x86: Rework identity map and TSS setup for larger BIOS sizes 

In order to support loading BIOSes > 256K, reorder the code, adjusting
the base if the kernel supports moving the identity map.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka 2011-01-21 21:48:18 +01:00 committed by Marcelo Tosatti
parent 94a8d39afd
commit 110761987d
1 changed files with 30 additions and 33 deletions
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63
target-i386/kvm.c
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@ -493,27 +493,9 @@ static int kvm_get_supported_msrs(KVMState *s)
return ret;
}
static int kvm_init_identity_map_page(KVMState *s)
{
#ifdef KVM_CAP_SET_IDENTITY_MAP_ADDR
int ret;
uint64_t addr = 0xfffbc000;
if (!kvm_check_extension(s, KVM_CAP_SET_IDENTITY_MAP_ADDR)) {
return 0;
}
ret = kvm_vm_ioctl(s, KVM_SET_IDENTITY_MAP_ADDR, &addr);
if (ret < 0) {
fprintf(stderr, "kvm_set_identity_map_addr: %s\n", strerror(ret));
return ret;
}
#endif
return 0;
}
int kvm_arch_init(KVMState *s)
{
uint64_t identity_base = 0xfffbc000;
int ret;
struct utsname utsname;
@ -525,27 +507,42 @@ int kvm_arch_init(KVMState *s)
uname(&utsname);
lm_capable_kernel = strcmp(utsname.machine, "x86_64") == 0;
/* create vm86 tss. KVM uses vm86 mode to emulate 16-bit code
* directly. In order to use vm86 mode, a TSS is needed. Since this
* must be part of guest physical memory, we need to allocate it. */
/* this address is 3 pages before the bios, and the bios should present
* as unavaible memory. FIXME, need to ensure the e820 map deals with
* this?
*/
/*
* Tell fw_cfg to notify the BIOS to reserve the range.
* On older Intel CPUs, KVM uses vm86 mode to emulate 16-bit code directly.
* In order to use vm86 mode, an EPT identity map and a TSS are needed.
* Since these must be part of guest physical memory, we need to allocate
* them, both by setting their start addresses in the kernel and by
* creating a corresponding e820 entry. We need 4 pages before the BIOS.
*
* Older KVM versions may not support setting the identity map base. In
* that case we need to stick with the default, i.e. a 256K maximum BIOS
* size.
*/
if (e820_add_entry(0xfffbc000, 0x4000, E820_RESERVED) < 0) {
perror("e820_add_entry() table is full");
exit(1);
#ifdef KVM_CAP_SET_IDENTITY_MAP_ADDR
if (kvm_check_extension(s, KVM_CAP_SET_IDENTITY_MAP_ADDR)) {
/* Allows up to 16M BIOSes. */
identity_base = 0xfeffc000;
ret = kvm_vm_ioctl(s, KVM_SET_IDENTITY_MAP_ADDR, &identity_base);
if (ret < 0) {
return ret;
}
}
ret = kvm_vm_ioctl(s, KVM_SET_TSS_ADDR, 0xfffbd000);
#endif
/* Set TSS base one page after EPT identity map. */
ret = kvm_vm_ioctl(s, KVM_SET_TSS_ADDR, identity_base + 0x1000);
if (ret < 0) {
return ret;
}
return kvm_init_identity_map_page(s);
/* Tell fw_cfg to notify the BIOS to reserve the range. */
ret = e820_add_entry(identity_base, 0x4000, E820_RESERVED);
if (ret < 0) {
fprintf(stderr, "e820_add_entry() table is full\n");
return ret;
}
return 0;
}
static void set_v8086_seg(struct kvm_segment *lhs, const SegmentCache *rhs)