linux-kernel - Re: [PATCH v2 5/6] xen/x86/pvh: Add 32-bit PVH initialization code

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Date:	Fri, 17 Jul 2015 11:21:36 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:	david.vrabel@...rix.com, roger.pau@...rix.com,
	elena.ufimtseva@...cle.com, stefano.stabellini@...citrix.com,
	tim@....org, jbeulich@...e.com, andrew.cooper3@...rix.com,
	ian.campbell@...rix.com, ian.jackson@...citrix.com,
	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/6] xen/x86/pvh: Add 32-bit PVH initialization code

On Thu, Jul 16, 2015 at 05:43:40PM -0400, Boris Ostrovsky wrote:
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> ---
> Changes in v2:
> * Some code reshuffling due to changes in patch 1.
> 
>  arch/x86/xen/enlighten.c |  4 ----
>  arch/x86/xen/smp.c       | 16 +++++++++-------
>  arch/x86/xen/xen-head.S  | 13 ++++++++++++-
>  3 files changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index d665b1d..9eb395f 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1461,10 +1461,6 @@ static void __init xen_pvh_early_guest_init(void)
>  
>  	xen_pvh_early_cpu_init(0);
>  	xen_pvh_set_cr_flags(0);
> -
> -#ifdef CONFIG_X86_32
> -	BUG(); /* PVH: Implement proper support. */
> -#endif
>  }
>  #endif    /* CONFIG_XEN_PVH */
>  
> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> index 33a4529..f8c5d23 100644
> --- a/arch/x86/xen/smp.c
> +++ b/arch/x86/xen/smp.c
> @@ -372,11 +372,8 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
>  
>  	gdt = get_cpu_gdt_table(cpu);
>  
> -#ifdef CONFIG_X86_32
> -	/* Note: PVH is not yet supported on x86_32. */
> -	ctxt->user_regs.fs = __KERNEL_PERCPU;
> -	ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
> -#endif
> +	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
> +	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
>  
>  	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
>  		ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
> @@ -403,6 +400,8 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
>  		ctxt->kernel_sp = idle->thread.sp0;
>  
>  #ifdef CONFIG_X86_32
> +		ctxt->user_regs.fs = __KERNEL_PERCPU;
> +		ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
>  		ctxt->event_callback_cs     = __KERNEL_CS;
>  		ctxt->failsafe_callback_cs  = __KERNEL_CS;
>  #else
> @@ -424,11 +423,14 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
>  		 */
>  		ctxt->user_regs.eip =
>  			(unsigned long)xen_pvh_early_cpu_init_secondary;
> +#ifdef CONFIG_X86_64
>  		ctxt->user_regs.rdi = cpu;
> +#else
> +		*((uint32_t *)ctxt->user_regs.esp + 1) = cpu;
> +#endif
>  	}
>  #endif
> -	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
> -	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
> +
>  	if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
>  		BUG();
>  
> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
> index 944b08b..eada11b 100644
> --- a/arch/x86/xen/xen-head.S
> +++ b/arch/x86/xen/xen-head.S
> @@ -55,7 +55,11 @@ ENTRY(startup_xen)
>   * @cpu:   this cpu number (%rdi)
>   */
>  ENTRY(xen_pvh_early_cpu_init)
> +#ifdef CONFIG_X86_64
>  	mov	%rbx, -8(%rsp)
> +#else
> +	mov	%ebx, -4(%esp)
> +#endif
>  	xor	%esi, %esi
>  	jmp	1f
>  
> @@ -70,13 +74,20 @@ ENTRY(xen_pvh_early_cpu_init_secondary)
>  
>  	mov     $MSR_EFER, %ecx
>  	rdmsr
> +#ifdef CONFIG_X86_64
>  	bts     $_EFER_SCE, %eax
> -
> +#endif
>  	bt      $20, %ebx
>  	jnc     2f      	/* No NX, skip setting it */
>  	bts     $_EFER_NX, %eax
>  2:	wrmsr
> +
> +#ifdef CONFIG_X86_64
>  	mov	-8(%rsp), %rbx
> +#else
> +	mov	-4(%esp), %ebx
> +#endif
> +
>  #ifdef CONFIG_SMP
>  	cmp     $0, %esi
>  	jne     cpu_bringup_and_idle
> -- 
> 1.8.1.4
> 
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