Re: [Xen-devel] [PATCH v3 11/14] AMD/IOMMU: adjust setup of internal interrupt for x2APIC mode

[Jan Beulich <JBeulich@xxxxxxxx>]

On 19.07.2019 19:31, Andrew Cooper wrote:
> On 16/07/2019 17:39, Jan Beulich wrote:
>> --- a/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
>> +++ b/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
>> @@ -416,6 +416,25 @@ union amd_iommu_ext_features {
>>        } flds;
>>    };
>>    
>> +/* x2APIC Control Registers */
>> +#define IOMMU_XT_INT_CTRL_MMIO_OFFSET               0x0170
>> +#define IOMMU_XT_PPR_INT_CTRL_MMIO_OFFSET   0x0178
>> +#define IOMMU_XT_GA_INT_CTRL_MMIO_OFFSET    0x0180
>> +
>> +union amd_iommu_x2apic_control {
>> +    uint64_t raw;
>> +    struct {
>> +        unsigned int :2;
>> +        unsigned int dest_mode:1;
>> +        unsigned int :5;
>> +        unsigned int dest_lo:24;
>> +        unsigned int vector:8;
>> +        unsigned int int_type:1; /* DM in IOMMU spec 3.04 */
>> +        unsigned int :15;
>> +        unsigned int dest_hi:8;
> 
> Bool bitfields like you've done elsewhere in v3?

I'd been considering this, but decided against because of ...

+static void set_x2apic_affinity(struct irq_desc *desc, const cpumask_t *mask)
+{
+    struct amd_iommu *iommu = desc->action->dev_id;
+    unsigned int dest = set_desc_affinity(desc, mask);
+    union amd_iommu_x2apic_control ctrl = {};
+    unsigned long flags;
+
+    if ( dest == BAD_APICID )
+        return;
+
+    msi_compose_msg(desc->arch.vector, NULL, &iommu->msi.msg);
+    iommu->msi.msg.dest32 = dest;
+
+    ctrl.dest_mode = MASK_EXTR(iommu->msi.msg.address_lo,
+                               MSI_ADDR_DESTMODE_MASK);
+    ctrl.int_type = MASK_EXTR(iommu->msi.msg.data,
+                              MSI_DATA_DELIVERY_MODE_MASK);

... this: We really mean a value copy here, not an "is zero" or
"is non-zero" one. I also think that both fields are not suitably
named for being boolean. In the recent re-work of struct
IO_APIC_route_entry (ca9310b24e) similar fields similarly were
left as "unsigned int". MSI's struct msg_data also falls into the
same category. I think if we wanted to switch to bool here, we
should do so everywhere at the same time (along with suitably
renaming fields).

Jan
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