On 09.10.25 18:37, Jan Beulich wrote:
On 09.10.2025 17:08, Grygorii Strashko wrote:
On 08.10.25 15:09, Jan Beulich wrote:
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -31,10 +31,13 @@
   #include <public/hvm/ioreq.h>
   #include <public/hvm/params.h>
-#define LVT_BIAS(reg) (((reg) - APIC_LVTT) >> 4)
+#include <../cpu/mcheck/x86_mca.h> /* MCG_CMCI_P */

This include... You probably do not like it also
It is dependency outside HVM code.

I've been thinking about something like vlapic->caps which can be filed before 
vlapic_init()
or passed as parameter, but seems x86 toolstack is considered to be able 
overwrite anything,
including v->arch.vmce.

Seems, no better options here.

Same here, hence why I used it despite not liking it.

@@ -697,8 +701,17 @@ int guest_rdmsr_x2apic(const struct vcpu
           return X86EMUL_EXCEPTION;
offset = reg << 4;
-    if ( offset == APIC_ICR )
+    switch ( offset )
+    {
+    case APIC_ICR:
           high = (uint64_t)vlapic_read_aligned(vlapic, APIC_ICR2) << 32;
+        break;
+
+    case APIC_CMCI:
+        if ( !(v->arch.vmce.mcg_cap & MCG_CMCI_P) )

Could it be done using wrapper, like vmce_has_cmci()?
As this is Intel specific it's candidate to be opt-out eventually.

Possible. I wanted to limit the churn, hence why I preferred not to introduce
a wrapper. Such an abstraction I wouldn't like to be a function taking a vCPU;
really this should be a domain property imo.

My intention was to limit spreading direct access to "vmce" data over vlapic 
code:

static bool vlapic_has_cmci(const struct vcpu *v)
{
        return v->arch.vmce.mcg_cap & MCG_CMCI_P;
}

Just expressing opinion.

--
Best regards,
-grygorii


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