diff mbox series

[v2,06/12] viridian: use softirq batching in hvcall_ipi()

Message ID 20201120094900.1489-7-paul@xen.org (mailing list archive)
State Superseded
Headers show
Series viridian: add support for ExProcessorMasks | expand

Commit Message

Paul Durrant Nov. 20, 2020, 9:48 a.m. UTC 
From: Paul Durrant <pdurrant@amazon.com>

vlapic_ipi() uses a softirq batching mechanism to improve the efficiency of
sending a IPIs to large number of processors. This patch modifies send_ipi()
(the worker function called by hvcall_ipi()) to also make use of the
mechanism when there multiple bits set the hypercall_vpmask.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Wei Liu <wl@xen.org>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>

v2:
 - Don't add the 'nr' field to struct hypercall_vpmask and use
   bitmap_weight() instead
---
 xen/arch/x86/hvm/viridian/viridian.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Comments

Jan Beulich Nov. 20, 2020, 3:11 p.m. UTC | #1 
On 20.11.2020 10:48, Paul Durrant wrote:
> From: Paul Durrant <pdurrant@amazon.com>
> 
> vlapic_ipi() uses a softirq batching mechanism to improve the efficiency of
> sending a IPIs to large number of processors. This patch modifies send_ipi()
> (the worker function called by hvcall_ipi()) to also make use of the
> mechanism when there multiple bits set the hypercall_vpmask.
> 
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>

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

Patch

diff --git a/xen/arch/x86/hvm/viridian/viridian.c b/xen/arch/x86/hvm/viridian/viridian.c
index d8d8ecc89c80..d6f47b28c1e6 100644
--- a/xen/arch/x86/hvm/viridian/viridian.c
+++ b/xen/arch/x86/hvm/viridian/viridian.c
@@ -11,6 +11,7 @@ 
 #include <xen/hypercall.h>
 #include <xen/domain_page.h>
 #include <xen/param.h>
+#include <xen/softirq.h>
 #include <asm/guest/hyperv-tlfs.h>
 #include <asm/paging.h>
 #include <asm/p2m.h>
@@ -570,6 +571,11 @@  static unsigned int vpmask_next(struct hypercall_vpmask *vpmask, unsigned int vp
 	      (vp) < HVM_MAX_VCPUS; \
 	      (vp) = vpmask_next(vpmask, vp) )
 
+static unsigned int vpmask_nr(const struct hypercall_vpmask *vpmask)
+{
+    return bitmap_weight(vpmask->mask, HVM_MAX_VCPUS);
+}
+
 /*
  * Windows should not issue the hypercalls requiring this callback in the
  * case where vcpu_id would exceed the size of the mask.
@@ -653,10 +659,17 @@  static int hvcall_flush(union hypercall_input *input,
 static void send_ipi(struct hypercall_vpmask *vpmask, uint8_t vector)
 {
     struct domain *currd = current->domain;
+    unsigned int nr = vpmask_nr(vpmask);
     unsigned int vp;
 
+    if ( nr > 1 )
+        cpu_raise_softirq_batch_begin();
+
     for_each_vp ( vpmask, vp )
         vlapic_set_irq(vcpu_vlapic(currd->vcpu[vp]), vector, 0);
+
+    if ( nr > 1 )
+        cpu_raise_softirq_batch_finish();
 }
 
 static int hvcall_ipi(union hypercall_input *input,