diff mbox series

[v3,3/6] x86/vpic: force int output to low when in init mode

Message ID 20210126134521.25784-4-roger.pau@citrix.com (mailing list archive)
State New, archived
Headers show
Series x86/intr: HVM guest interrupt handling fixes/cleanup | expand

Commit Message

Roger Pau Monne Jan. 26, 2021, 1:45 p.m. UTC 
When the PIC is on the init sequence prevent interrupt delivery. The
state of the registers is in the process of being set during the init
phase, so it makes sense to prevent any int line changes during that
process.

Requested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Changes since v2:
 - New in this version.
---
 xen/arch/x86/hvm/vpic.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Jan Beulich Jan. 26, 2021, 4:50 p.m. UTC | #1 
On 26.01.2021 14:45, Roger Pau Monne wrote:
> When the PIC is on the init sequence prevent interrupt delivery. The
> state of the registers is in the process of being set during the init
> phase, so it makes sense to prevent any int line changes during that
> process.
> 
> Requested-by: Jan Beulich <jbeulich@suse.com>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Acked-by: Jan Beulich <jbeulich@suse.com>

I guess I'll change the other tag in this case to Suggested-by
though, should I end up committing this.

Jan
diff mbox series

Patch

diff --git a/xen/arch/x86/hvm/vpic.c b/xen/arch/x86/hvm/vpic.c
index c1c1de7fd0..9195155ff0 100644
--- a/xen/arch/x86/hvm/vpic.c
+++ b/xen/arch/x86/hvm/vpic.c
@@ -101,11 +101,14 @@  static void vpic_update_int_output(struct hvm_hw_vpic *vpic)
     irq = vpic_get_highest_priority_irq(vpic);
     TRACE_3D(TRC_HVM_EMUL_PIC_INT_OUTPUT, vpic->int_output, vpic->is_master,
              irq);
-    if ( vpic->int_output == (irq >= 0) )
+    if ( vpic->int_output == (!vpic->init_state && irq >= 0) )
         return;
 
-    /* INT line transition L->H or H->L. */
-    vpic->int_output = !vpic->int_output;
+    /*
+     * INT line transition L->H or H->L.
+     * Force line status to L when in init mode.
+     */
+    vpic->int_output = !vpic->init_state && !vpic->int_output;
 
     if ( vpic->int_output )
     {