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kvm: Fix kernel boot IP

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Booting to a Linux kernel is no longer supported.  Therefore, start executing
at offset 0x200 of bzImage which has a jump to real-mode setup code.  See
Documentation/x86/boot.txt for more details.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This commit is contained in:
Pekka Enberg
2015-06-01 16:39:38 +01:00
committed by Will Deacon
parent 147c74c2e7
commit edc8a14d5b
2 changed files with 21 additions and 8 deletions
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include/kvm/kvm.h
+3
View File
@@ -15,6 +15,9 @@ struct kvm {
uint64_t ram_size;
void *ram_start;
uint16_t boot_cs;
uint16_t boot_ip;
struct kvm_regs regs;
struct kvm_sregs sregs;
};
kvm.c
+18 -8
View File
@@ -156,7 +156,7 @@ static inline uint32_t segment_to_flat(uint16_t selector, uint16_t offset)
#define BOOT_LOADER_CS 0x0000
#define BOOT_LOADER_IP 0x7c00
static int load_flat_binary(struct kvm *kvm, int fd)
static int load_flat_binary(struct kvm *self, int fd)
{
void *p;
int nr;
@@ -164,11 +164,14 @@ static int load_flat_binary(struct kvm *kvm, int fd)
if (lseek(fd, 0, SEEK_SET) < 0)
die_perror("lseek");
p = guest_addr_to_host(kvm, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
p = guest_addr_to_host(self, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
while ((nr = read(fd, p, 65536)) > 0)
p += nr;
self->boot_cs = BOOT_LOADER_CS;
self->boot_ip = BOOT_LOADER_IP;
return true;
}
@@ -182,7 +185,7 @@ static const char *BZIMAGE_MAGIC = "HdrS";
#define BZ_DEFAULT_SETUP_SECTS 4
static bool load_bzimage(struct kvm *kvm, int fd)
static bool load_bzimage(struct kvm *self, int fd)
{
unsigned long setup_sects;
struct boot_params boot;
@@ -211,16 +214,23 @@ static bool load_bzimage(struct kvm *kvm, int fd)
setup_sects = BZ_DEFAULT_SETUP_SECTS;
setup_size = setup_sects << 9;
p = guest_addr_to_host(kvm, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
p = guest_addr_to_host(self, segment_to_flat(BOOT_LOADER_CS, BOOT_LOADER_IP));
if (read(fd, p, setup_size) != setup_size)
die_perror("read");
p = guest_addr_to_host(kvm, BZ_KERNEL_START);
p = guest_addr_to_host(self, BZ_KERNEL_START);
while ((nr = read(fd, p, 65536)) > 0)
p += nr;
self->boot_cs = BOOT_LOADER_CS;
/*
* The real-mode setup code starts at offset 0x200 of a bzImage. See
* Documentation/x86/boot.txt for details.
*/
self->boot_ip = BOOT_LOADER_IP + 0x200;
return true;
}
@@ -270,8 +280,8 @@ void kvm__reset_vcpu(struct kvm *self)
* KVM on Intel requires 'base' to be 'selector * 16' in
* real mode.
*/
.selector = BOOT_LOADER_CS,
.base = BOOT_LOADER_CS * 16,
.selector = self->boot_cs,
.base = self->boot_cs * 16,
.limit = 0xffffU,
.type = 0x0bU,
.present = 1,
@@ -335,7 +345,7 @@ void kvm__reset_vcpu(struct kvm *self)
die_perror("KVM_SET_SREGS failed");
self->regs = (struct kvm_regs) {
.rip = BOOT_LOADER_IP,
.rip = self->boot_ip,
/* We start the guest in 16-bit real mode */
.rflags = 0x0000000000000002ULL,
};