[PATCH 03/10] viridian: introduce a per-cpu hypercall_vpmask and accessor functions...

[Paul Durrant <paul@xxxxxxx>]

From: Paul Durrant <pdurrant@xxxxxxxxxx>

... and make use of them in hvcall_flush()/need_flush().

Subsequent patches will need to deal with virtual processor masks potentially
wider than 64 bits. Thus, to avoid using too much stack, this patch
introduces global per-cpu virtual processor masks and converts the
implementation of hvcall_flush() to use them.

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Wei Liu <wl@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/hvm/viridian/viridian.c | 51 +++++++++++++++++++++++++---
 1 file changed, 47 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/viridian/viridian.c 
b/xen/arch/x86/hvm/viridian/viridian.c
index c4f720f58d6d..4ab1f14b2248 100644
--- a/xen/arch/x86/hvm/viridian/viridian.c
+++ b/xen/arch/x86/hvm/viridian/viridian.c
@@ -507,15 +507,41 @@ void viridian_domain_deinit(struct domain *d)
     XFREE(d->arch.hvm.viridian);
 }
 
+struct hypercall_vpmask {
+    DECLARE_BITMAP(mask, HVM_MAX_VCPUS);
+};
+
+static DEFINE_PER_CPU(struct hypercall_vpmask, hypercall_vpmask);
+
+static void vpmask_empty(struct hypercall_vpmask *vpmask)
+{
+    bitmap_zero(vpmask->mask, HVM_MAX_VCPUS);
+}
+
+static void vpmask_set(struct hypercall_vpmask *vpmask, unsigned int vp)
+{
+    __set_bit(vp, vpmask->mask);
+}
+
+static void vpmask_fill(struct hypercall_vpmask *vpmask)
+{
+    bitmap_fill(vpmask->mask, HVM_MAX_VCPUS);
+}
+
+static bool vpmask_test(struct hypercall_vpmask *vpmask, unsigned int vp)
+{
+    return test_bit(vp, vpmask->mask);
+}
+
 /*
  * Windows should not issue the hypercalls requiring this callback in the
  * case where vcpu_id would exceed the size of the mask.
  */
 static bool need_flush(void *ctxt, struct vcpu *v)
 {
-    uint64_t vcpu_mask = *(uint64_t *)ctxt;
+    struct hypercall_vpmask *vpmask = ctxt;
 
-    return vcpu_mask & (1ul << v->vcpu_id);
+    return vpmask_test(vpmask, v->vcpu_id);
 }
 
 union hypercall_input {
@@ -546,6 +572,7 @@ static int hvcall_flush(union hypercall_input *input,
                         unsigned long input_params_gpa,
                         unsigned long output_params_gpa)
 {
+    struct hypercall_vpmask *vpmask = &this_cpu(hypercall_vpmask);
     struct {
         uint64_t address_space;
         uint64_t flags;
@@ -567,13 +594,29 @@ static int hvcall_flush(union hypercall_input *input,
      * so err on the safe side.
      */
     if ( input_params.flags & HV_FLUSH_ALL_PROCESSORS )
-        input_params.vcpu_mask = ~0ul;
+        vpmask_fill(vpmask);
+    else
+    {
+        unsigned int vp;
+
+        vpmask_empty(vpmask);
+        for (vp = 0; vp < 64; vp++)
+        {
+            if ( !input_params.vcpu_mask )
+                break;
+
+            if ( input_params.vcpu_mask & 1 )
+                vpmask_set(vpmask, vp);
+
+            input_params.vcpu_mask >>= 1;
+        }
+    }
 
     /*
      * A false return means that another vcpu is currently trying
      * a similar operation, so back off.
      */
-    if ( !paging_flush_tlb(need_flush, &input_params.vcpu_mask) )
+    if ( !paging_flush_tlb(need_flush, vpmask) )
         return -ERESTART;
 
     output->rep_complete = input->rep_count;
-- 
2.20.1