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kvm: Hardcode a "reset vector" at f000:fff0

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It seems that if we attempt to run code at any other location than f000:fff0,
we get an KVM_EXIT_UNKNOWN error. To work around that, hardcode a "reset
vector" at f000:fff0 that jumps to 0000:0x7c000 and load the kernel at the
latter location.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This commit is contained in:
Pekka Enberg
2010-03-27 10:53:15 +02:00
committed by Will Deacon
parent e93ab78a73
commit 2a601aafee
2 changed files with 27 additions and 6 deletions
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kvm.c
+25 -6
View File
@@ -153,8 +153,13 @@ static inline uint32_t segment_to_flat(uint16_t selector, uint16_t offset)
return ((uint32_t)selector << 4) + (uint32_t) offset;
}
#define BIN_BOOT_LOADER_CS 0xf000
#define BIN_BOOT_LOADER_IP 0xfff0
#define RESET_CS 0xf000
#define RESET_IP 0xfff0
#define BIN_BOOT_LOADER_CS 0x0000
#define BIN_BOOT_LOADER_IP 0x7c00
static unsigned char reset_code[] = { 0xea, 0x00, 0x7c, 0x00, 0x00 };
static int load_flat_binary(struct kvm *kvm, int fd)
{
@@ -169,8 +174,12 @@ static int load_flat_binary(struct kvm *kvm, int fd)
while ((nr = read(fd, p, 65536)) > 0)
p += nr;
kvm->boot_cs = BIN_BOOT_LOADER_CS;
kvm->boot_ip = BIN_BOOT_LOADER_IP;
p = guest_addr_to_host(kvm, segment_to_flat(RESET_CS, RESET_IP));
memcpy(p, reset_code, ARRAY_SIZE(reset_code));
kvm->boot_cs = RESET_CS;
kvm->boot_ip = RESET_IP;
return true;
}
@@ -230,8 +239,12 @@ static bool load_bzimage(struct kvm *kvm, int fd)
while ((nr = read(fd, p, 65536)) > 0)
p += nr;
kvm->boot_cs = 0;
kvm->boot_ip = BZ_BOOT_LOADER_START;
p = guest_addr_to_host(kvm, segment_to_flat(RESET_CS, RESET_IP));
memcpy(p, reset_code, ARRAY_SIZE(reset_code));
kvm->boot_cs = RESET_CS;
kvm->boot_ip = RESET_IP;
return true;
}
@@ -457,6 +470,12 @@ void kvm__show_code(struct kvm *self)
unsigned int i;
uint8_t *ip;
if (ioctl(self->vcpu_fd, KVM_GET_REGS, &self->regs) < 0)
die("KVM_GET_REGS failed");
if (ioctl(self->vcpu_fd, KVM_GET_SREGS, &self->sregs) < 0)
die("KVM_GET_SREGS failed");
ip = guest_addr_to_host(self, ip_real_to_flat(self, self->regs.rip) - code_prologue);
printf("Code: ");
util.h
+2
View File
@@ -1,6 +1,8 @@
#ifndef UTIL_H_
#define UTIL_H_
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
/*
* Some bits are stolen from perf tool :)
*/