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kvm: x86: Fix initial kvm_has_msr_star 

KVM_GET_MSR_INDEX_LIST returns -E2BIG when the provided space is too
small for all MSRs. But this is precisely the error we trigger with the
initial request in order to obtain that size. Do not fail in that case.

This caused a subtle corruption of the guest state as MSR_STAR was not
properly saved/restored. The corruption became visible with latest kvm
optimizing the MSR updates.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit 6fb6d24554)
This commit is contained in:
Jan Kiszka 2009-12-06 15:51:24 +01:00 committed by Anthony Liguori
parent ea6112b165
commit 20c1a35211
1 changed files with 2 additions and 2 deletions
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4
target-i386/kvm.c
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@ -244,9 +244,9 @@ static int kvm_has_msr_star(CPUState *env)
* save/restore */
msr_list.nmsrs = 0;
ret = kvm_ioctl(env->kvm_state, KVM_GET_MSR_INDEX_LIST, &msr_list);
if (ret < 0)
if (ret < 0 && ret != -E2BIG) {
return 0;
}
/* Old kernel modules had a bug and could write beyond the provided
memory. Allocate at least a safe amount of 1K. */
kvm_msr_list = qemu_mallocz(MAX(1024, sizeof(msr_list) +