[PATCH] x86/vmx: reorder code in vmx_deliver_posted_intr

Roger Pau Monne posted 1 patch 1 week ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/xen tags/patchew/20200730140309.59916-1-roger.pau@citrix.com
xen/arch/x86/hvm/vmx/vmx.c | 55 ++++++++++++++++++--------------------
1 file changed, 26 insertions(+), 29 deletions(-)

[PATCH] x86/vmx: reorder code in vmx_deliver_posted_intr

Posted by Roger Pau Monne 1 week ago
Remove the unneeded else branch, which allows to reduce the
indentation of a larger block of code, while making the flow of the
function more obvious.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/hvm/vmx/vmx.c | 55 ++++++++++++++++++--------------------
 1 file changed, 26 insertions(+), 29 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index eb54aadfba..7773dcae1b 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2003,6 +2003,8 @@ static void __vmx_deliver_posted_interrupt(struct vcpu *v)
 
 static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
 {
+    struct pi_desc old, new, prev;
+
     if ( pi_test_and_set_pir(vector, &v->arch.hvm.vmx.pi_desc) )
         return;
 
@@ -2014,41 +2016,36 @@ static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
          * VMEntry as it used to be.
          */
         pi_set_on(&v->arch.hvm.vmx.pi_desc);
+        vcpu_kick(v);
+        return;
     }
-    else
-    {
-        struct pi_desc old, new, prev;
 
-        prev.control = v->arch.hvm.vmx.pi_desc.control;
+    prev.control = v->arch.hvm.vmx.pi_desc.control;
 
-        do {
-            /*
-             * Currently, we don't support urgent interrupt, all
-             * interrupts are recognized as non-urgent interrupt,
-             * Besides that, if 'ON' is already set, no need to
-             * sent posted-interrupts notification event as well,
-             * according to hardware behavior.
-             */
-            if ( pi_test_sn(&prev) || pi_test_on(&prev) )
-            {
-                vcpu_kick(v);
-                return;
-            }
-
-            old.control = v->arch.hvm.vmx.pi_desc.control &
-                          ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
-            new.control = v->arch.hvm.vmx.pi_desc.control |
-                          (1 << POSTED_INTR_ON);
+    do {
+        /*
+         * Currently, we don't support urgent interrupt, all
+         * interrupts are recognized as non-urgent interrupt,
+         * Besides that, if 'ON' is already set, no need to
+         * sent posted-interrupts notification event as well,
+         * according to hardware behavior.
+         */
+        if ( pi_test_sn(&prev) || pi_test_on(&prev) )
+        {
+            vcpu_kick(v);
+            return;
+        }
 
-            prev.control = cmpxchg(&v->arch.hvm.vmx.pi_desc.control,
-                                   old.control, new.control);
-        } while ( prev.control != old.control );
+        old.control = v->arch.hvm.vmx.pi_desc.control &
+                      ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
+        new.control = v->arch.hvm.vmx.pi_desc.control |
+                      (1 << POSTED_INTR_ON);
 
-        __vmx_deliver_posted_interrupt(v);
-        return;
-    }
+        prev.control = cmpxchg(&v->arch.hvm.vmx.pi_desc.control,
+                               old.control, new.control);
+    } while ( prev.control != old.control );
 
-    vcpu_kick(v);
+    __vmx_deliver_posted_interrupt(v);
 }
 
 static void vmx_sync_pir_to_irr(struct vcpu *v)
-- 
2.28.0


Re: [PATCH] x86/vmx: reorder code in vmx_deliver_posted_intr

Posted by Jan Beulich 1 week ago
On 30.07.2020 16:03, Roger Pau Monne wrote:
> Remove the unneeded else branch, which allows to reduce the
> indentation of a larger block of code, while making the flow of the
> function more obvious.
> 
> No functional change intended.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

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

One minor request (could likely be taken care of while
committing):

> @@ -2014,41 +2016,36 @@ static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
>           * VMEntry as it used to be.
>           */
>          pi_set_on(&v->arch.hvm.vmx.pi_desc);
> +        vcpu_kick(v);
> +        return;
>      }
> -    else
> -    {
> -        struct pi_desc old, new, prev;
>  
> -        prev.control = v->arch.hvm.vmx.pi_desc.control;
> +    prev.control = v->arch.hvm.vmx.pi_desc.control;
>  
> -        do {
> -            /*
> -             * Currently, we don't support urgent interrupt, all
> -             * interrupts are recognized as non-urgent interrupt,
> -             * Besides that, if 'ON' is already set, no need to
> -             * sent posted-interrupts notification event as well,
> -             * according to hardware behavior.
> -             */
> -            if ( pi_test_sn(&prev) || pi_test_on(&prev) )
> -            {
> -                vcpu_kick(v);
> -                return;
> -            }
> -
> -            old.control = v->arch.hvm.vmx.pi_desc.control &
> -                          ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
> -            new.control = v->arch.hvm.vmx.pi_desc.control |
> -                          (1 << POSTED_INTR_ON);
> +    do {
> +        /*
> +         * Currently, we don't support urgent interrupt, all
> +         * interrupts are recognized as non-urgent interrupt,
> +         * Besides that, if 'ON' is already set, no need to
> +         * sent posted-interrupts notification event as well,
> +         * according to hardware behavior.
> +         */

Would be nice to s/sent/send/ here as you move it (maybe also
remove the plural from "posted-interrupts") and - if possible -
re-flow for the now increased space on the right side.

Jan

Re: [PATCH] x86/vmx: reorder code in vmx_deliver_posted_intr

Posted by Roger Pau Monné 1 week ago
On Fri, Jul 31, 2020 at 03:05:52PM +0200, Jan Beulich wrote:
> On 30.07.2020 16:03, Roger Pau Monne wrote:
> > Remove the unneeded else branch, which allows to reduce the
> > indentation of a larger block of code, while making the flow of the
> > function more obvious.
> > 
> > No functional change intended.
> > 
> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> 
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> 
> One minor request (could likely be taken care of while
> committing):
> 
> > @@ -2014,41 +2016,36 @@ static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
> >           * VMEntry as it used to be.
> >           */
> >          pi_set_on(&v->arch.hvm.vmx.pi_desc);
> > +        vcpu_kick(v);
> > +        return;
> >      }
> > -    else
> > -    {
> > -        struct pi_desc old, new, prev;
> >  
> > -        prev.control = v->arch.hvm.vmx.pi_desc.control;
> > +    prev.control = v->arch.hvm.vmx.pi_desc.control;
> >  
> > -        do {
> > -            /*
> > -             * Currently, we don't support urgent interrupt, all
> > -             * interrupts are recognized as non-urgent interrupt,
> > -             * Besides that, if 'ON' is already set, no need to
> > -             * sent posted-interrupts notification event as well,
> > -             * according to hardware behavior.
> > -             */
> > -            if ( pi_test_sn(&prev) || pi_test_on(&prev) )
> > -            {
> > -                vcpu_kick(v);
> > -                return;
> > -            }
> > -
> > -            old.control = v->arch.hvm.vmx.pi_desc.control &
> > -                          ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
> > -            new.control = v->arch.hvm.vmx.pi_desc.control |
> > -                          (1 << POSTED_INTR_ON);
> > +    do {
> > +        /*
> > +         * Currently, we don't support urgent interrupt, all
> > +         * interrupts are recognized as non-urgent interrupt,
> > +         * Besides that, if 'ON' is already set, no need to
> > +         * sent posted-interrupts notification event as well,
> > +         * according to hardware behavior.
> > +         */
> 
> Would be nice to s/sent/send/ here as you move it (maybe also
> remove the plural from "posted-interrupts") and - if possible -
> re-flow for the now increased space on the right side.

Oh, sure, I should have realized myself. Feel free to adjust at commit
if you don't mind. I would also adjust 'non-urgent interrupts'.

Thanks, Roger.