From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: [PATCH 1/2] x86/vmx: Don't clobber exception_bitmap when entering/leaving emulated real mode Date: Wed, 27 Jan 2016 18:11:12 +0000 Message-ID: <1453918273-23008-1-git-send-email-andrew.cooper3@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Xen-devel Cc: Andrew Cooper , Kevin Tian , Jun Nakajima , Jan Beulich List-Id: xen-devel@lists.xenproject.org Most updates to the exception bitmaps set or clear an individual bits. However, entering or exiting emulated real mode unilaterally clobbers it, leaving the exit code to recalculate what it should have been. This is error prone, and indeed currently fails to recalculate the TRAP_no_device intercept appropriately. Instead of overwriting exception_bitmap when entering emulated real mode, move the override into vmx_update_exception_bitmap() and leave exception_bitmap unmodified. This means that recalculation is unnecessary, and that the use of vmx_fpu_leave() and vmx_update_debug_state() while in emulated real mode doesn't result in TRAP_no_device and TRAP_int3 being un-intercepted. This is only a functional change on hardware lacking unrestricted guest support. Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Jun Nakajima CC: Kevin Tian --- xen/arch/x86/hvm/vmx/vmx.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 04dde83..4f9951f 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -389,10 +389,13 @@ void vmx_update_secondary_exec_control(struct vcpu *v) void vmx_update_exception_bitmap(struct vcpu *v) { + u32 bitmap = unlikely(v->arch.hvm_vmx.vmx_realmode) + ? 0xffffffffu : v->arch.hvm_vmx.exception_bitmap; + if ( nestedhvm_vcpu_in_guestmode(v) ) - nvmx_update_exception_bitmap(v, v->arch.hvm_vmx.exception_bitmap); + nvmx_update_exception_bitmap(v, bitmap); else - __vmwrite(EXCEPTION_BITMAP, v->arch.hvm_vmx.exception_bitmap); + __vmwrite(EXCEPTION_BITMAP, bitmap); } static int vmx_guest_x86_mode(struct vcpu *v) @@ -1306,8 +1309,6 @@ static void vmx_update_guest_cr(struct vcpu *v, unsigned int cr) { for ( s = x86_seg_cs ; s <= x86_seg_tr ; s++ ) vmx_set_segment_register(v, s, ®[s]); - v->arch.hvm_vmx.exception_bitmap = 0xffffffff; - vmx_update_exception_bitmap(v); } else { @@ -1315,13 +1316,9 @@ static void vmx_update_guest_cr(struct vcpu *v, unsigned int cr) if ( !(v->arch.hvm_vmx.vm86_segment_mask & (1<arch.hvm_vmx.vm86_saved_seg[s]); - v->arch.hvm_vmx.exception_bitmap = HVM_TRAP_MASK - | (paging_mode_hap(v->domain) ? - 0 : (1U << TRAP_page_fault)) - | (1U << TRAP_no_device); - vmx_update_exception_bitmap(v); - vmx_update_debug_state(v); } + + vmx_update_exception_bitmap(v); } v->arch.hvm_vcpu.hw_cr[0] = -- 2.1.4