Commit 807c1425 authored Nov 02, 2014 by Nadav Amit Committed by Paolo Bonzini Nov 07, 2014

KVM: x86: SYSCALL cannot clear eflags[1]

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>

parent b5bbf10e

arch/x86/kvm/emulate.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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 */

Admin message