Re: [Xen-devel] [PATCH v2 1/7] x86/vioapic: introduce a internal vIO APIC structure

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.03.17 at 18:49, <roger.pau@xxxxxxxxxx> wrote:
> Yes, I think the unnamed structure is way better, here's what I've done:
> 
> save.h:
> 
> union vioapic_redir_entry
> {
>     uint64_t bits;
>     struct {
>         uint8_t vector;
>         uint8_t delivery_mode:3;
>         uint8_t dest_mode:1;
>         uint8_t delivery_status:1;
>         uint8_t polarity:1;
>         uint8_t remote_irr:1;
>         uint8_t trig_mode:1;
>         uint8_t mask:1;
>         uint8_t reserve:7;
>         uint8_t reserved[4];
>         uint8_t dest_id;
>     } fields;
> };
> 
> #define VIOAPIC_NUM_PINS  48 /* 16 ISA IRQs, 32 non-legacy PCI IRQS. */
> 
> #define DECLARE_VIOAPIC(name, cnt)                      \
>     struct name {                                       \
>         uint64_t base_address;                          \
>         uint32_t ioregsel;                              \
>         uint32_t id;                                    \
>         union vioapic_redir_entry redirtbl[cnt];        \
>     }
> 
> DECLARE_VIOAPIC(hvm_hw_vioapic, VIOAPIC_NUM_PINS);
> 
> #ifndef __XEN__
> #undef DECLARE_VIOAPIC
> #endif
> 
> vioapic.h:
> 
> struct hvm_vioapic {
>     struct domain *domain;
>     DECLARE_VIOAPIC(, VIOAPIC_NUM_PINS);
> };
> 
> This seems to work fine, and now the BUILD_BUG_ON is just pointless.

Well, no, not entirely. As said you still want to exclude alignment
effects prior structure members of hvm_vioapic may have (please
continue to not make assumptions on the alignment of the first
field of the structure here).

Furthermore, despite the #undef the macro name should start
with XEN_, perhaps even with XEN_HVM_. Whether the
DECLARE part is really needed/useful I'm not sure.

Jan


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