| Message ID | 1453918273-23008-1-git-send-email-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 27.01.16 at 19:11, <andrew.cooper3@citrix.com> wrote: > 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 <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> From: Andrew Cooper [mailto:andrew.cooper3@citrix.com] > Sent: Thursday, January 28, 2016 2:11 AM > > 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 <andrew.cooper3@citrix.com> Acked-by: Kevin Tian <kevin.tian@intel.com>
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<<s)) ) vmx_set_segment_register( v, s, &v->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] =
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 <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Jun Nakajima <jun.nakajima@intel.com> CC: Kevin Tian <kevin.tian@intel.com> --- xen/arch/x86/hvm/vmx/vmx.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)