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

From: Konrad Rzeszutek Wilk
Date: Tue Jul 07 2015 - 16:00:09 EST


On Mon, Jul 06, 2015 at 11:34:24PM -0400, Boris Ostrovsky wrote:
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

A little bit more here I think - as in that the parameter
passing is not an Xen specific thing but something this
code cooked up?

> ---
> arch/x86/xen/enlighten.c | 4 ----
> arch/x86/xen/smp.c | 17 ++++++++++-------
> arch/x86/xen/xen-head.S | 17 +++++++++++++++--
> 3 files changed, 25 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 7953e68..807337e 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1464,10 +1464,6 @@ static void __init xen_pvh_early_guest_init(void)
>
> xen_pvh_early_cpu_init(0, false);
> 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 7cf0765..99be53b 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
> @@ -424,12 +423,16 @@ 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;
> ctxt->user_regs.rsi = true; /* entry == true */
> +#else
> + *((uint32_t *)ctxt->user_regs.esp + 1) = cpu;
> + *((uint32_t *)ctxt->user_regs.esp + 2) = true;
> +#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 b1508a8..12c4e2a 100644
> --- a/arch/x86/xen/xen-head.S
> +++ b/arch/x86/xen/xen-head.S
> @@ -51,14 +51,18 @@ ENTRY(startup_xen)
>
> #ifdef CONFIG_XEN_PVH
> /*
> - * xen_pvh_early_cpu_init() - early PVH VCPU initialization
> + * xen_pvh_early_cpu_init(cpu, entry) - early PVH VCPU initialization
> * @cpu: this cpu number (%rdi)
> * @entry: true if this is a secondary vcpu coming up on this entry
> * point, false if this is the boot CPU being initialized for
> * the first time (%rsi)

Should this be updated to reflect how it is to be done on 32-bit (as in
not using %rdi and %rsi?)
> */
> ENTRY(xen_pvh_early_cpu_init)
> +#ifdef CONFIG_X86_64
> mov %rbx, -8(%rsp)
> +#else
> + mov %ebx, -4(%esp)
> +#endif
>
> /* Entry point for secondary CPUs */
> ENTRY(xen_pvh_early_cpu_init_secondary)
> @@ -69,15 +73,24 @@ 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 1f /* No NX, skip setting it */
> bts $_EFER_NX, %eax
> 1: wrmsr
> +
> +#ifdef CONFIG_X86_64
> mov -8(%rsp), %rbx
> -#ifdef CONFIG_SMP
> cmp $0, %esi
> +#else
> + mov -4(%esp), %ebx
> + cmp $0, 8(%esp) /* second argument */
> +#endif
> +
> +#ifdef CONFIG_SMP
> jne cpu_bringup_and_idle
> #endif
> ret
> --
> 1.8.1.4
>
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