[PATCH v3] x86/vmx: Avoid pausing on HVM_PARAM_IDENT_PT in additional cases

[Teddy Astie <teddy.astie@xxxxxxxxxx>]

When settings HVM_PARAM_IDENT_PT, skip domain pausing when :
- there is no vcpu
- unrestricted guest capability is used

Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
---
Regarding checking for hvm_paging_enabled(v) (proposed in v2 review), we can't
as hvm_paging_enabled() is vCPU specific, and vCPU 0 may have a different value
to another one.

v3:
 - rebased patches with staging
 - adjusted formatting

v2:
 - rebased patches with staging

 xen/arch/x86/hvm/hvm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 9a4147b62e..2981a61cee 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4237,11 +4237,14 @@ static int hvm_set_param(struct domain *d, uint32_t 
index, uint64_t value)
             rc = -EINVAL;
         break;
     case HVM_PARAM_IDENT_PT:
+        v = domain_vcpu(d, 0);
+
         /*
          * Only actually required for VT-x lacking unrestricted_guest
          * capabilities.  Short circuit the pause if possible.
          */
-        if ( paging_mode_shadow(d) || !using_vmx() )
+        if ( paging_mode_shadow(d) || !using_vmx() || !v ||
+             vmx_unrestricted_guest(v) )
             break;
 
         /*
-- 
2.55.0



--
Teddy Astie | Vates XCP-ng Developer

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