From 037fe82cf5fadf0f74c3da70560ee7592a8f2083 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Mon, 30 Jul 2018 11:26:53 +0200 Subject: [PATCH] x86/vmx: Don't clobber %dr6 while debugging state is lazy MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit c/s 4f36452b63 introduced a write to %dr6 in the #DB intercept case, but the guests debug registers may be lazy at this point, at which point the guests later attempt to read %dr6 will discard this value and use the older stale value. Signed-off-by: Andrew Cooper Reviewed-by: Roger Pau Monné Acked-by: Kevin Tian master commit: 3cdac2805692c7accde2f405d81cc0be799aee48 master date: 2018-07-19 14:06:48 +0100 --- xen/arch/x86/hvm/vmx/vmx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 610c8d6eb9..7189820bfc 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -3701,6 +3701,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs) */ __vmread(EXIT_QUALIFICATION, &exit_qualification); HVMTRACE_1D(TRAP_DEBUG, exit_qualification); + __restore_debug_registers(v); write_debugreg(6, exit_qualification | DR_STATUS_RESERVED_ONE); if ( !v->domain->debugger_attached ) { -- 2.30.2