Re: [Xen-devel] [PATCH v3 4/9] arm/vm_event: get/set registers

[Julien Grall <julien.grall@xxxxxxx>]

Hi Tamas,

On 04/05/16 15:51, Tamas K Lengyel wrote:
> diff --git a/xen/include/asm-arm/vm_event.h b/xen/include/asm-arm/vm_event.h
> index a3fc4ce..814d0da 100644
> --- a/xen/include/asm-arm/vm_event.h
> +++ b/xen/include/asm-arm/vm_event.h
> @@ -48,15 +48,10 @@ void vm_event_register_write_resume(struct vcpu *v, 
> vm_event_response_t *rsp)
>       /* Not supported on ARM. */
>   }
>
> -static inline
> -void vm_event_set_registers(struct vcpu *v, vm_event_response_t *rsp)
> -{
> -    /* Not supported on ARM. */
> -}
> +void vm_event_set_registers(struct vcpu *v, vm_event_response_t *rsp);
>
> -static inline void vm_event_fill_regs(vm_event_request_t *req)
> -{
> -    /* Not supported on ARM. */
> -}
> +void vm_event_fill_regs(vm_event_request_t *req,
> +                        const struct cpu_user_regs *regs,
> +                        struct domain *d);
>
>   #endif /* __ASM_ARM_VM_EVENT_H__ */
> diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
> index 3acf217..fabeee8 100644
> --- a/xen/include/public/vm_event.h
> +++ b/xen/include/public/vm_event.h
> @@ -129,8 +129,8 @@
>   #define VM_EVENT_X86_XCR0   3
>
>   /*
> - * Using a custom struct (not hvm_hw_cpu) so as to not fill
> - * the vm_event ring buffer too quickly.
> + * Using custom vCPU structs (i.e. not hvm_hw_cpu) for both x86 and ARM
You may want to rework this sentence as hvm_hw_cpu does not exist on 
ARM/ARM64.
> + * so as to not fill the vm_event ring buffer too quickly.
>    */
>   struct vm_event_regs_x86 {
>       uint64_t rax;
> @@ -168,6 +168,54 @@ struct vm_event_regs_x86 {
>       uint32_t _pad;
>   };
>
> +struct vm_event_regs_arm32 {
> +    uint32_t r0_usr;
> +    uint32_t r1_usr;
> +    uint32_t r2_usr;
> +    uint32_t r3_usr;
> +    uint32_t r4_usr;
> +    uint32_t r5_usr;
> +    uint32_t r6_usr;
> +    uint32_t r7_usr;
> +    uint32_t r8_usr;
> +    uint32_t r9_usr;
> +    uint32_t r10_usr;
> +    uint32_t r12_usr;
> +    uint32_t lr_usr;
> +    uint32_t sp_usr;
> +    uint32_t sp_svc;
> +    uint32_t spsr_svc;
> +    uint32_t fp;
> +    uint32_t pc;
> +    uint32_t cpsr;
> +    uint32_t ttbr0;
> +    uint32_t ttbr1;
> +};
> +
> +struct vm_event_regs_arm64 {
> +    uint64_t x0;
> +    uint64_t x1;
> +    uint64_t x2;
> +    uint64_t x3;
> +    uint64_t x4;
> +    uint64_t x5;
> +    uint64_t x6;
> +    uint64_t x7;
> +    uint64_t x8;
> +    uint64_t x9;
> +    uint64_t x10;
> +    uint64_t x16;
> +    uint64_t lr;
> +    uint64_t sp_el0;
> +    uint64_t sp_el1;
> +    uint32_t spsr_el1;
> +    uint64_t fp;
> +    uint64_t pc;
> +    uint32_t cpsr;
> +    uint64_t ttbr0;
> +    uint64_t ttbr1;
> +};
By defining 2 distinct structures, it will be more difficult for the 
introspection tools to inspect registers of an Aarch64 domain running in 
AArch32 mode. They wouldn't be able to re-use code for AArch32 domain 
because the structure fields are different.
The ARM ARM (see D1.20.1 in ARM DDI 0487A.i) provides a mapping between 
AArch32 state and AArch64 state. If you use it to define the layout of a 
common structure, the support of AArch32 state for AArch64 domain will 
come free.
> +
>   /*
>    * mem_access flag definitions
>    *
> @@ -256,6 +304,8 @@ typedef struct vm_event_st {
>       union {
>           union {
>               struct vm_event_regs_x86 x86;
> +            struct vm_event_regs_arm32 arm32;
> +            struct vm_event_regs_arm64 arm64;
>           } regs;
>
>           struct vm_event_emul_read_data emul_read_data;
Regards,

--
Julien Grall

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