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kvm: Fill up fake IVT

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Fill up fake IVT to point to 2 bytes opcodes of "sti,iret". Since they have to
live somewhere in guest memory we use _pad entry from boot_params space.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This commit is contained in:
Cyrill Gorcunov
2015-06-01 16:39:38 +01:00
committed by Will Deacon
parent ea68482839
commit 60489bb901
1 changed files with 13 additions and 6 deletions
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kvm.c
+13 -6
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@@ -198,10 +198,10 @@ static const char *BZIMAGE_MAGIC = "HdrS";
static bool load_bzimage(struct kvm *self, int fd, const char *kernel_cmdline)
{
unsigned long setup_sects;
struct boot_params boot;
struct boot_params boot, *t;
struct ivt_entry real_mode_irq;
ssize_t setup_size;
void *p;
void *p, *v;
int nr;
/*
@@ -247,15 +247,22 @@ static bool load_bzimage(struct kvm *self, int fd, const char *kernel_cmdline)
* Setup a *fake* real mode IVT, it has only one real
* hadler which does just iret
*/
/*
* we need a place for 2 bytes so lets do
* a hack and use spare place in bootparams
*/
t = (struct boot_params *)guest_real_to_host(self, BOOT_LOADER_SELECTOR, BOOT_LOADER_IP);
v = guest_flat_to_host(self, 0);
t->hdr._pad2[0] = 0xfb; /* sti */
t->hdr._pad2[1] = 0xcf; /* iret */
nr = (void *)&t->hdr._pad2[0] - v;
real_mode_irq = (struct ivt_entry) {
.segment = 0,
.offset = 0x400 + 1,
.segment = nr >> 4,
.offset = (nr - (nr & ~0xf)),
};
ivt_set_all(real_mode_irq);
p = guest_flat_to_host(self, 0);
ivt_copy_table(p, IVT_VECTORS * sizeof(real_mode_irq));
p += IVT_VECTORS * sizeof(real_mode_irq) + 1;
*(char *)p = 0xcf; /* iret here */
return true;
}