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[PATCH] KVM: Do not export unsupported msrs to userspace 

Some msrs, such as MSR_STAR, are not available on all processors.  Exporting
them causes qemu to try to fetch them, which will fail.

So, check all msrs for validity at module load time.

Signed-off-by: Michael Riepe <michael@mr511.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Michael Riepe 2006-12-22 01:05:36 -08:00 committed by Linus Torvalds
parent 2c26495710
commit bf591b24d0
1 changed files with 24 additions and 3 deletions
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27
drivers/kvm/kvm_main.c
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@ -1417,6 +1417,9 @@ static int kvm_dev_ioctl_set_sregs(struct kvm *kvm, struct kvm_sregs *sregs)
/*
* List of msr numbers which we expose to userspace through KVM_GET_MSRS
* and KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST.
*
* This list is modified at module load time to reflect the
* capabilities of the host cpu.
*/
static u32 msrs_to_save[] = {
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
@ -1427,6 +1430,22 @@ static u32 msrs_to_save[] = {
MSR_IA32_TIME_STAMP_COUNTER,
};
static unsigned num_msrs_to_save;
static __init void kvm_init_msr_list(void)
{
u32 dummy[2];
unsigned i, j;
for (i = j = 0; i < ARRAY_SIZE(msrs_to_save); i++) {
if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0)
continue;
if (j < i)
msrs_to_save[j] = msrs_to_save[i];
j++;
}
num_msrs_to_save = j;
}
/*
* Adapt set_msr() to msr_io()'s calling convention
@ -1735,15 +1754,15 @@ static long kvm_dev_ioctl(struct file *filp,
if (copy_from_user(&msr_list, user_msr_list, sizeof msr_list))
goto out;
n = msr_list.nmsrs;
msr_list.nmsrs = ARRAY_SIZE(msrs_to_save);
msr_list.nmsrs = num_msrs_to_save;
if (copy_to_user(user_msr_list, &msr_list, sizeof msr_list))
goto out;
r = -E2BIG;
if (n < ARRAY_SIZE(msrs_to_save))
if (n < num_msrs_to_save)
goto out;
r = -EFAULT;
if (copy_to_user(user_msr_list->indices, &msrs_to_save,
sizeof msrs_to_save))
num_msrs_to_save * sizeof(u32)))
goto out;
r = 0;
}
@ -1894,6 +1913,8 @@ static __init int kvm_init(void)
kvm_init_debug();
kvm_init_msr_list();
if ((bad_page = alloc_page(GFP_KERNEL)) == NULL) {
r = -ENOMEM;
goto out;