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KVM: x86: SYSCALL cannot clear eflags[1]

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SYSCALL emulation currently clears in 64-bit mode eflags according to
MSR_SYSCALL_MASK.  However, on bare-metal eflags[1] which is fixed to one
cannot be cleared, even if MSR_SYSCALL_MASK masks the bit.  This wrong behavior
may result in failed VM-entry, as VT disallows entry with eflags[1] cleared.

This patch sets the bit after masking eflags on syscall.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-11-02 11:54:49 +02:00 committed by Paolo Bonzini
parent b5bbf10ee6
commit 807c142595
1 changed files with 1 additions and 0 deletions
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arch/x86/kvm/emulate.c
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@ -2306,6 +2306,7 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt)
ops->get_msr(ctxt, MSR_SYSCALL_MASK, &msr_data);
ctxt->eflags &= ~msr_data;
ctxt->eflags |= EFLG_RESERVED_ONE_MASK;
#endif
} else {
/* legacy mode */