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Re: [Xen-devel] [PATCH v1 02/12] xen/hvmlite: Factor out common kernel init code



On Fri, Jan 22, 2016 at 04:35:48PM -0500, Boris Ostrovsky wrote:
> HVMlite guests (to be introduced in subsequent patches) share most
> of the kernel initialization code with PV(H).
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
>  arch/x86/xen/enlighten.c |  225 
> ++++++++++++++++++++++++----------------------
>  1 files changed, 119 insertions(+), 106 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index d09e4c9..2cf446a 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1505,19 +1505,14 @@ static void __init xen_pvh_early_guest_init(void)
>  }
>  #endif    /* CONFIG_XEN_PVH */
>  
> -/* First C function to be called on Xen boot */
> -asmlinkage __visible void __init xen_start_kernel(void)
> +
> +static void __init xen_init_kernel(void)
>  {
>       struct physdev_set_iopl set_iopl;
>       unsigned long initrd_start = 0;
>       u64 pat;
>       int rc;
>  
> -     if (!xen_start_info)
> -             return;
> -
> -     xen_domain_type = XEN_PV_DOMAIN;
> -
>       xen_setup_features();
>  #ifdef CONFIG_XEN_PVH
>       xen_pvh_early_guest_init();
> @@ -1529,48 +1524,9 @@ asmlinkage __visible void __init xen_start_kernel(void)
>       if (xen_initial_domain())
>               pv_info.features |= PV_SUPPORTED_RTC;
>       pv_init_ops = xen_init_ops;
> -     if (!xen_pvh_domain()) {
> -             pv_cpu_ops = xen_cpu_ops;
> -
> -             x86_platform.get_nmi_reason = xen_get_nmi_reason;
> -     }
> -
> -     if (xen_feature(XENFEAT_auto_translated_physmap))
> -             x86_init.resources.memory_setup = xen_auto_xlated_memory_setup;
> -     else
> -             x86_init.resources.memory_setup = xen_memory_setup;
> -     x86_init.oem.arch_setup = xen_arch_setup;
> -     x86_init.oem.banner = xen_banner;
>  
>       xen_init_time_ops();
>  
> -     /*
> -      * Set up some pagetable state before starting to set any ptes.
> -      */
> -
> -     xen_init_mmu_ops();
> -
> -     /* Prevent unwanted bits from being set in PTEs. */
> -     __supported_pte_mask &= ~_PAGE_GLOBAL;
> -
> -     /*
> -      * Prevent page tables from being allocated in highmem, even
> -      * if CONFIG_HIGHPTE is enabled.
> -      */
> -     __userpte_alloc_gfp &= ~__GFP_HIGHMEM;
> -
> -     /* Work out if we support NX */
> -     x86_configure_nx();
> -
> -     /* Get mfn list */
> -     xen_build_dynamic_phys_to_machine();
> -
> -     /*
> -      * Set up kernel GDT and segment registers, mainly so that
> -      * -fstack-protector code can be executed.
> -      */
> -     xen_setup_gdt(0);
> -
>       xen_init_irq_ops();
>       xen_init_cpuid_mask();
>  
> @@ -1580,21 +1536,8 @@ asmlinkage __visible void __init xen_start_kernel(void)
>        */
>       xen_init_apic();
>  #endif
> -
> -     if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
> -             pv_mmu_ops.ptep_modify_prot_start = xen_ptep_modify_prot_start;
> -             pv_mmu_ops.ptep_modify_prot_commit = 
> xen_ptep_modify_prot_commit;
> -     }
> -
>       machine_ops = xen_machine_ops;
>  
> -     /*
> -      * The only reliable way to retain the initial address of the
> -      * percpu gdt_page is to remember it here, so we can go and
> -      * mark it RW later, when the initial percpu area is freed.
> -      */
> -     xen_initial_gdt = &per_cpu(gdt_page, 0);
> -
>       xen_smp_init();
>  
>  #ifdef CONFIG_ACPI_NUMA
> @@ -1609,66 +1552,126 @@ asmlinkage __visible void __init 
> xen_start_kernel(void)
>          possible map and a non-dummy shared_info. */
>       per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
>  
> -     local_irq_disable();
> -     early_boot_irqs_disabled = true;
> +     if (!xen_hvm_domain()) {
> +             if (!xen_pvh_domain()) {
> +                     pv_cpu_ops = xen_cpu_ops;
>  
> -     xen_raw_console_write("mapping kernel into physical memory\n");
> -     xen_setup_kernel_pagetable((pgd_t *)xen_start_info->pt_base,
> -                                xen_start_info->nr_pages);
> -     xen_reserve_special_pages();
> +                     x86_platform.get_nmi_reason = xen_get_nmi_reason;
> +             }
>  
> -     /*
> -      * Modify the cache mode translation tables to match Xen's PAT
> -      * configuration.
> -      */
> -     rdmsrl(MSR_IA32_CR_PAT, pat);
> -     pat_init_cache_modes(pat);
> +             if (xen_feature(XENFEAT_auto_translated_physmap))
> +                     x86_init.resources.memory_setup =
> +                             xen_auto_xlated_memory_setup;
> +             else
> +                     x86_init.resources.memory_setup = xen_memory_setup;
> +             x86_init.oem.arch_setup = xen_arch_setup;
> +             x86_init.oem.banner = xen_banner;
>  
> -     /* keep using Xen gdt for now; no urgent need to change it */
> +             /*
> +              * Set up some pagetable state before starting to set any ptes.
> +              */
>  
> -#ifdef CONFIG_X86_32
> -     pv_info.kernel_rpl = 1;
> -     if (xen_feature(XENFEAT_supervisor_mode_kernel))
> -             pv_info.kernel_rpl = 0;
> -#else
> -     pv_info.kernel_rpl = 0;
> -#endif
> -     /* set the limit of our address space */
> -     xen_reserve_top();
> +             xen_init_mmu_ops();
> +
> +             /* Prevent unwanted bits from being set in PTEs. */
> +             __supported_pte_mask &= ~_PAGE_GLOBAL;
>  
> -     /* PVH: runs at default kernel iopl of 0 */
> -     if (!xen_pvh_domain()) {
>               /*
> -              * We used to do this in xen_arch_setup, but that is too late
> -              * on AMD were early_cpu_init (run before ->arch_setup()) calls
> -              * early_amd_init which pokes 0xcf8 port.
> +              * Prevent page tables from being allocated in highmem, even
> +              * if CONFIG_HIGHPTE is enabled.
>                */
> -             set_iopl.iopl = 1;
> -             rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
> -             if (rc != 0)
> -                     xen_raw_printk("physdev_op failed %d\n", rc);
> -     }
> +             __userpte_alloc_gfp &= ~__GFP_HIGHMEM;
> +
> +             /* Work out if we support NX */
> +             x86_configure_nx();
> +
> +             /* Get mfn list */
> +             xen_build_dynamic_phys_to_machine();
> +
> +             /*
> +              * Set up kernel GDT and segment registers, mainly so that
> +              * -fstack-protector code can be executed.
> +              */
> +             xen_setup_gdt(0);
> +
> +             if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
> +                     pv_mmu_ops.ptep_modify_prot_start =
> +                             xen_ptep_modify_prot_start;
> +                     pv_mmu_ops.ptep_modify_prot_commit =
> +                             xen_ptep_modify_prot_commit;
> +             }
> +
> +             /*
> +              * The only reliable way to retain the initial address of the
> +              * percpu gdt_page is to remember it here, so we can go and
> +              * mark it RW later, when the initial percpu area is freed.
> +              */
> +             xen_initial_gdt = &per_cpu(gdt_page, 0);
> +
> +             xen_raw_console_write("mapping kernel into physical memory\n");
> +             xen_setup_kernel_pagetable((pgd_t *)xen_start_info->pt_base,
> +                                        xen_start_info->nr_pages);
> +             xen_reserve_special_pages();
> +
> +             /*
> +              * Modify the cache mode translation tables to match Xen's PAT
> +              * configuration.
> +              */
> +             rdmsrl(MSR_IA32_CR_PAT, pat);
> +             pat_init_cache_modes(pat);
> +
> +             /* keep using Xen gdt for now; no urgent need to change it */
>  
>  #ifdef CONFIG_X86_32
> -     /* set up basic CPUID stuff */
> -     cpu_detect(&new_cpu_data);
> -     set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU);
> -     new_cpu_data.wp_works_ok = 1;
> -     new_cpu_data.x86_capability[0] = cpuid_edx(1);
> +             pv_info.kernel_rpl = 1;
> +             if (xen_feature(XENFEAT_supervisor_mode_kernel))
> +                     pv_info.kernel_rpl = 0;
> +#else
> +             pv_info.kernel_rpl = 0;
> +#endif
> +             /* set the limit of our address space */
> +             xen_reserve_top();
> +
> +             /* PVH: runs at default kernel iopl of 0 */
> +             if (!xen_pvh_domain()) {
> +                     /*
> +                      * We used to do this in xen_arch_setup, but that is
> +                      * too late on AMD were early_cpu_init (run before
> +                      * ->arch_setup()) calls early_amd_init which pokes
> +                      * 0xcf8 port.
> +                      */
> +                     set_iopl.iopl = 1;
> +                     rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl,
> +                                                &set_iopl);
> +                     if (rc != 0)
> +                             xen_raw_printk("physdev_op failed %d\n", rc);
> +             }
> +
> +#ifdef CONFIG_X86_32
> +             /* set up basic CPUID stuff */
> +             cpu_detect(&new_cpu_data);
> +             set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU);
> +             new_cpu_data.wp_works_ok = 1;
> +             new_cpu_data.x86_capability[0] = cpuid_edx(1);
>  #endif

Whoa, I'm lost, its hard for me to tell what exactly stayed and what
got pulled into a helper, etc. Is there a possibility to split this
patch in 2 somehow to make the actual functional changes easier to
read? There are too many changes here and I just can't tell easily
what's going on.

  Luis

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