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[09/21] KVM: x86: SYSCALL cannot clear eflags[1]

Message ID 1414922101-17626-10-git-send-email-namit@cs.technion.ac.il (mailing list archive)
State New, archived
Headers show

Commit Message

Nadav Amit Nov. 2, 2014, 9:54 a.m. UTC 
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>
---
 arch/x86/kvm/emulate.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox

Patch

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index e624d62..f1484bb 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2286,6 +2286,7 @@  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 */