From: Nadav Amit <namit@cs.technion.ac.il>
Date: Sun, 2 Nov 2014 09:54:49 +0000 (+0200)
Subject: KVM: x86: SYSCALL cannot clear eflags[1]
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=807c142595abcb99285746bd5512447bdf40b9b1;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

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>
---

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 713295d913fd..e475cdff15e1 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -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 */