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Re: [PATCH v4 2/8] xen/common: dom0less: make some parts of Arm's CONFIG_DOM0LESS common



On Mon, 5 May 2025, Oleksii Kurochko wrote:
> Move some parts of Arm's Dom0Less code to be reused by other architectures.
> At the moment, RISC-V is going to reuse these parts.
> 
> Move dom0less-build.h from the Arm-specific directory to asm-generic
> as these header is expected to be the same across acrhictectures with
> some updates: add the following declaration of construct_domU(),
> and arch_create_domUs() as there are some parts which are still
> architecture-specific.
> 
> Introduce HAS_DOM0LESS to provide ability to enable generic Dom0less
> code for an architecture.
> 
> Relocate the CONFIG_DOM0LESS configuration to the common with adding
> "depends on HAS_DOM0LESS" to not break builds for architectures which
> don't support CONFIG_DOM0LESS config, especically it would be useful
> to not provide stubs for  construct_domU(), arch_create_domUs()
> in case of *-randconfig which may set CONFIG_DOM0LESS=y.
> 
> Move is_dom0less_mode() function to the common code, as it depends on
> boot modules that are already part of the common code.
> 
> Move create_domUs() function to the common code with some updates:
> - Add arch_create_domUs() to cover parsing of arch-specific features,
>   for example, SVE (Scalar Vector Extension ) exists only in Arm.
> 
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> ---
> Changes in v4:
> - Add HAS_DEVICE_TREE dependency to DOM0LESS_BOOT config and
>   drop 'select HAS_DEVICE_TREE' from HAS_DOM0LESS.
> - Move forward declaration of 'struct domain' outside #ifdef 
> CONFIG_DOM0LESS_BOOT
>   as it is used by an argument of set_xs_domain().
> - Add Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>.
> - Drop footer after commit message: the change of dom0less to something else
>   (predefined domains or similar) will be done separately, outside this patch
>   series.
> - Add EMACS stuff at the end of dom0less-build.c file.
> - Wrap "d_cfg.max_grant_frames = gnttab_dom0_frames();" by #ifdef 
> CONFIG_GRANT_TABLE
>   as gnttab_dom0_frames() is only defined in case when CONFIG_GRANT_TABLE=y.
> - Update the commit message: drop info about arch_xen_domctl_createdomain() 
> as this
>   function was dropped in previous version of this patch.
> ---
> Changes in v3:
>  - Move changes connected to the patch "xen/arm: dom0less delay xenstore 
> initialization"
>    to common.
>    Also, some necessary parts for the mentioned patches were moved
>    to common (such as alloc_xenstore_evtchn(), ... ).
>    Not all changes are moved, changes connected to alloc_xenstore_params() and
>    construct_domu() will be moved in the following patches of this patch 
> series.
>  - Move parsing of capabilities property to common code.
>  - Align parsing of "passthrough", "multiboot,device-tree" properties with 
> staging.
>  - Drop arch_xen_domctl_createdomain().
>  - Add 'select HAS_DEVICE_TREE' for config HAS_DOM0LESS.
>  - Add empty lines after license in the top of newly added files.
>  - s/arch_create_domus/arch_create_domUs.
>  - Add footer below commit message regarding the naming of dom0less.
> ---
> Changes in v2:
>  - Convert 'depends on Arm' to 'depends on HAS_DOM0LESS' for
>    CONFIG_DOM0LESS_BOOT.
>  - Change 'default Arm' to 'default y' for CONFIG_DOM0LESS_BOOT as there is
>    dependency on HAS_DOM0LESS.
>  - Introduce HAS_DOM0LESS and enable it for Arm.
>  - Update the commit message.
> ---
>  xen/arch/arm/Kconfig                      |   9 +-
>  xen/arch/arm/dom0less-build.c             | 371 ++++------------------
>  xen/arch/arm/include/asm/Makefile         |   1 +
>  xen/arch/arm/include/asm/dom0less-build.h |  34 --
>  xen/common/Kconfig                        |  12 +
>  xen/common/device-tree/Makefile           |   1 +
>  xen/common/device-tree/dom0less-build.c   | 294 +++++++++++++++++
>  xen/include/asm-generic/dom0less-build.h  |  50 +++
>  8 files changed, 415 insertions(+), 357 deletions(-)
>  delete mode 100644 xen/arch/arm/include/asm/dom0less-build.h
>  create mode 100644 xen/common/device-tree/dom0less-build.c
>  create mode 100644 xen/include/asm-generic/dom0less-build.h
> 
> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> index da8a406f5a..d0e0a7753c 100644
> --- a/xen/arch/arm/Kconfig
> +++ b/xen/arch/arm/Kconfig
> @@ -15,6 +15,7 @@ config ARM
>       select GENERIC_UART_INIT
>       select HAS_ALTERNATIVE if HAS_VMAP
>       select HAS_DEVICE_TREE
> +     select HAS_DOM0LESS
>       select HAS_STACK_PROTECTOR
>       select HAS_UBSAN
>  
> @@ -120,14 +121,6 @@ config GICV2
>         Driver for the ARM Generic Interrupt Controller v2.
>         If unsure, say Y
>  
> -config DOM0LESS_BOOT
> -     bool "Dom0less boot support" if EXPERT
> -     default y
> -     help
> -       Dom0less boot support enables Xen to create and start domU guests 
> during
> -       Xen boot without the need of a control domain (Dom0), which could be
> -       present anyway.
> -
>  config GICV3
>       bool "GICv3 driver"
>       depends on !NEW_VGIC
> diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
> index a356fc94fc..ef49495d4f 100644
> --- a/xen/arch/arm/dom0less-build.c
> +++ b/xen/arch/arm/dom0less-build.c
> @@ -22,48 +22,7 @@
>  #include <asm/static-memory.h>
>  #include <asm/static-shmem.h>
>  
> -#define XENSTORE_PFN_LATE_ALLOC UINT64_MAX
> -
> -static domid_t __initdata xs_domid = DOMID_INVALID;
> -static bool __initdata need_xenstore;
> -
> -void __init set_xs_domain(struct domain *d)
> -{
> -    xs_domid = d->domain_id;
> -    set_global_virq_handler(d, VIRQ_DOM_EXC);
> -}
> -
> -bool __init is_dom0less_mode(void)
> -{
> -    struct bootmodules *mods = &bootinfo.modules;
> -    struct bootmodule *mod;
> -    unsigned int i;
> -    bool dom0found = false;
> -    bool domUfound = false;
> -
> -    /* Look into the bootmodules */
> -    for ( i = 0 ; i < mods->nr_mods ; i++ )
> -    {
> -        mod = &mods->module[i];
> -        /* Find if dom0 and domU kernels are present */
> -        if ( mod->kind == BOOTMOD_KERNEL )
> -        {
> -            if ( mod->domU == false )
> -            {
> -                dom0found = true;
> -                break;
> -            }
> -            else
> -                domUfound = true;
> -        }
> -    }
> -
> -    /*
> -     * If there is no dom0 kernel but at least one domU, then we are in
> -     * dom0less mode
> -     */
> -    return ( !dom0found && domUfound );
> -}
> +bool __initdata need_xenstore;
>  
>  #ifdef CONFIG_VGICV2
>  static int __init make_gicv2_domU_node(struct kernel_info *kinfo)
> @@ -686,25 +645,6 @@ static int __init prepare_dtb_domU(struct domain *d, 
> struct kernel_info *kinfo)
>      return -EINVAL;
>  }
>  
> -static int __init alloc_xenstore_evtchn(struct domain *d)
> -{
> -    evtchn_alloc_unbound_t alloc;
> -    int rc;
> -
> -    alloc.dom = d->domain_id;
> -    alloc.remote_dom = xs_domid;
> -    rc = evtchn_alloc_unbound(&alloc, 0);
> -    if ( rc )
> -    {
> -        printk("Failed allocating event channel for domain\n");
> -        return rc;
> -    }
> -
> -    d->arch.hvm.params[HVM_PARAM_STORE_EVTCHN] = alloc.port;
> -
> -    return 0;
> -}
> -
>  #define XENSTORE_PFN_OFFSET 1
>  static int __init alloc_xenstore_page(struct domain *d)
>  {
> @@ -771,36 +711,6 @@ static int __init alloc_xenstore_params(struct 
> kernel_info *kinfo)
>      return rc;
>  }
>  
> -static void __init initialize_domU_xenstore(void)
> -{
> -    struct domain *d;
> -
> -    if ( xs_domid == DOMID_INVALID )
> -        return;
> -
> -    for_each_domain( d )
> -    {
> -        uint64_t gfn = d->arch.hvm.params[HVM_PARAM_STORE_PFN];
> -        int rc;
> -
> -        if ( gfn == 0 )
> -            continue;
> -
> -        if ( is_xenstore_domain(d) )
> -            continue;
> -
> -        rc = alloc_xenstore_evtchn(d);
> -        if ( rc < 0 )
> -            panic("%pd: Failed to allocate xenstore_evtchn\n", d);
> -
> -        if ( gfn != XENSTORE_PFN_LATE_ALLOC && 
> IS_ENABLED(CONFIG_GRANT_TABLE) )
> -        {
> -            ASSERT(gfn < UINT32_MAX);
> -            gnttab_seed_entry(d, GNTTAB_RESERVED_XENSTORE, xs_domid, gfn);
> -        }
> -    }
> -}
> -
>  static void __init domain_vcpu_affinity(struct domain *d,
>                                          const struct dt_device_node *node)
>  {
> @@ -906,8 +816,8 @@ static inline int domain_p2m_set_allocation(struct domain 
> *d, uint64_t mem,
>  }
>  #endif /* CONFIG_ARCH_PAGING_MEMPOOL */
>  
> -static int __init construct_domU(struct domain *d,
> -                                 const struct dt_device_node *node)
> +int __init construct_domU(struct domain *d,
> +                          const struct dt_device_node *node)
>  {
>      struct kernel_info kinfo = KERNEL_INFO_INIT;
>      const char *dom0less_enhanced;
> @@ -1009,246 +919,77 @@ static int __init construct_domU(struct domain *d,
>      return alloc_xenstore_params(&kinfo);
>  }
>  
> -void __init create_domUs(void)
> +void __init arch_create_domUs(struct dt_device_node *node,
> +                       struct xen_domctl_createdomain *d_cfg,
> +                       unsigned int flags)
>  {
> -    struct dt_device_node *node;
> -    const char *dom0less_iommu;
> -    bool iommu = false;
> -    const struct dt_device_node *cpupool_node,
> -                                *chosen = dt_find_node_by_path("/chosen");
> -    const char *llc_colors_str = NULL;
> -
> -    BUG_ON(chosen == NULL);
> -    dt_for_each_child_node(chosen, node)
> -    {
> -        struct domain *d;
> -        struct xen_domctl_createdomain d_cfg = {
> -            .arch.gic_version = XEN_DOMCTL_CONFIG_GIC_NATIVE,
> -            .flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap,
> -            /*
> -             * The default of 1023 should be sufficient for guests because
> -             * on ARM we don't bind physical interrupts to event channels.
> -             * The only use of the evtchn port is inter-domain 
> communications.
> -             * 1023 is also the default value used in libxl.
> -             */
> -            .max_evtchn_port = 1023,
> -            .max_grant_frames = -1,
> -            .max_maptrack_frames = -1,
> -            .grant_opts = XEN_DOMCTL_GRANT_version(opt_gnttab_max_version),
> -        };
> -        unsigned int flags = 0U;
> -        bool has_dtb = false;
> -        uint32_t val;
> -        int rc;
> -
> -        if ( !dt_device_is_compatible(node, "xen,domain") )
> -            continue;
> -
> -        if ( (max_init_domid + 1) >= DOMID_FIRST_RESERVED )
> -            panic("No more domain IDs available\n");
> +    uint32_t val;
>  
> -        if ( dt_property_read_u32(node, "capabilities", &val) )
> -        {
> -            if ( val & ~DOMAIN_CAPS_MASK )
> -                panic("Invalid capabilities (%"PRIx32")\n", val);
> -
> -            if ( val & DOMAIN_CAPS_CONTROL )
> -                flags |= CDF_privileged;
> -
> -            if ( val & DOMAIN_CAPS_HARDWARE )
> -            {
> -                if ( hardware_domain )
> -                    panic("Only 1 hardware domain can be specified! (%pd)\n",
> -                           hardware_domain);
> -
> -                d_cfg.max_grant_frames = gnttab_dom0_frames();
> -                d_cfg.max_evtchn_port = -1;
> -                flags |= CDF_hardware;
> -                iommu = true;
> -            }
> -
> -            if ( val & DOMAIN_CAPS_XENSTORE )
> -            {
> -                if ( xs_domid != DOMID_INVALID )
> -                    panic("Only 1 xenstore domain can be specified! (%u)\n",
> -                          xs_domid);
> +    d_cfg->arch.gic_version = XEN_DOMCTL_CONFIG_GIC_NATIVE;
> +    d_cfg->flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap;

I did some more tests and discovered that this needs to be |= to modify
flags passed to it (e.g. XEN_DOMCTL_CDF_iommu), rather than reset them
completely. Overall, it should be

    d_cfg->flags |= XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap;

I'll fix it on commit
  
> -                d_cfg.flags |= XEN_DOMCTL_CDF_xs_domain;
> -                d_cfg.max_evtchn_port = -1;
> -            }
> -        }
> -
> -        if ( dt_find_property(node, "xen,static-mem", NULL) )
> -        {
> -            if ( llc_coloring_enabled )
> -                panic("LLC coloring and static memory are incompatible\n");
> -
> -            flags |= CDF_staticmem;
> -        }
> -
> -        if ( dt_property_read_bool(node, "direct-map") )
> -        {
> -            if ( !(flags & CDF_staticmem) )
> -                panic("direct-map is not valid for domain %s without static 
> allocation.\n",
> -                      dt_node_name(node));
> -
> -            flags |= CDF_directmap;
> -        }
> -
> -        if ( !dt_property_read_u32(node, "cpus", &d_cfg.max_vcpus) )
> -            panic("Missing property 'cpus' for domain %s\n",
> -                  dt_node_name(node));
> -
> -        if ( !dt_property_read_string(node, "passthrough", &dom0less_iommu) )
> -        {
> -            if ( flags & CDF_hardware )
> -                panic("Don't specify passthrough for hardware domain\n");
> -
> -            if ( !strcmp(dom0less_iommu, "enabled") )
> -                iommu = true;
> -        }
> -
> -        if ( (flags & CDF_hardware) && !(flags & CDF_directmap) &&
> -             !iommu_enabled )
> -            panic("non-direct mapped hardware domain requires iommu\n");
> -
> -        if ( dt_find_compatible_node(node, NULL, "multiboot,device-tree") )
> -        {
> -            if ( flags & CDF_hardware )
> -                panic("\"multiboot,device-tree\" incompatible with hardware 
> domain\n");
> -
> -            has_dtb = true;
> -        }
> -
> -        if ( iommu_enabled && (iommu || has_dtb) )
> -            d_cfg.flags |= XEN_DOMCTL_CDF_iommu;
> -
> -        if ( !dt_property_read_u32(node, "nr_spis", &d_cfg.arch.nr_spis) )
> -        {
> -            int vpl011_virq = GUEST_VPL011_SPI;
> -
> -            d_cfg.arch.nr_spis = VGIC_DEF_NR_SPIS;
> -
> -            /*
> -             * The VPL011 virq is GUEST_VPL011_SPI, unless direct-map is
> -             * set, in which case it'll match the hardware.
> -             *
> -             * Since the domain is not yet created, we can't use
> -             * d->arch.vpl011.irq. So the logic to find the vIRQ has to
> -             * be hardcoded.
> -             * The logic here shall be consistent with the one in
> -             * domain_vpl011_init().
> -             */
> -            if ( flags & CDF_directmap )
> -            {
> -                vpl011_virq = serial_irq(SERHND_DTUART);
> -                if ( vpl011_virq < 0 )
> -                    panic("Error getting IRQ number for this serial port 
> %d\n",
> -                          SERHND_DTUART);
> -            }
> +    if ( !dt_property_read_u32(node, "nr_spis", &d_cfg->arch.nr_spis) )
> +    {
> +        int vpl011_virq = GUEST_VPL011_SPI;
>  
> -            /*
> -             * vpl011 uses one emulated SPI. If vpl011 is requested, make
> -             * sure that we allocate enough SPIs for it.
> -             */
> -            if ( dt_property_read_bool(node, "vpl011") )
> -                d_cfg.arch.nr_spis = MAX(d_cfg.arch.nr_spis,
> -                                         vpl011_virq - 32 + 1);
> -        }
> -        else if ( flags & CDF_hardware )
> -            panic("nr_spis cannot be specified for hardware domain\n");
> +        d_cfg->arch.nr_spis = VGIC_DEF_NR_SPIS;
>  
> -        /* Get the optional property domain-cpupool */
> -        cpupool_node = dt_parse_phandle(node, "domain-cpupool", 0);
> -        if ( cpupool_node )
> +        /*
> +         * The VPL011 virq is GUEST_VPL011_SPI, unless direct-map is
> +         * set, in which case it'll match the hardware.
> +         *
> +         * Since the domain is not yet created, we can't use
> +         * d->arch.vpl011.irq. So the logic to find the vIRQ has to
> +         * be hardcoded.
> +         * The logic here shall be consistent with the one in
> +         * domain_vpl011_init().
> +         */
> +        if ( flags & CDF_directmap )
>          {
> -            int pool_id = btcpupools_get_domain_pool_id(cpupool_node);
> -            if ( pool_id < 0 )
> -                panic("Error getting cpupool id from domain-cpupool (%d)\n",
> -                      pool_id);
> -            d_cfg.cpupool_id = pool_id;
> +            vpl011_virq = serial_irq(SERHND_DTUART);
> +            if ( vpl011_virq < 0 )
> +                panic("Error getting IRQ number for this serial port %d\n",
> +                        SERHND_DTUART);
>          }
>  
> -        if ( dt_property_read_u32(node, "max_grant_version", &val) )
> -            d_cfg.grant_opts = XEN_DOMCTL_GRANT_version(val);
> +        /*
> +            * vpl011 uses one emulated SPI. If vpl011 is requested, make
> +            * sure that we allocate enough SPIs for it.
> +            */
> +        if ( dt_property_read_bool(node, "vpl011") )
> +            d_cfg->arch.nr_spis = MAX(d_cfg->arch.nr_spis,
> +                                      vpl011_virq - 32 + 1);
> +    }
> +    else if ( flags & CDF_hardware )
> +        panic("nr_spis cannot be specified for hardware domain\n");
>  
> -        if ( dt_property_read_u32(node, "max_grant_frames", &val) )
> -        {
> -            if ( val > INT32_MAX )
> -                panic("max_grant_frames (%"PRIu32") overflow\n", val);
> -            d_cfg.max_grant_frames = val;
> -        }
> +    if ( dt_get_property(node, "sve", &val) )
> +    {
> +#ifdef CONFIG_ARM64_SVE
> +        unsigned int sve_vl_bits;
> +        bool ret = false;
>  
> -        if ( dt_property_read_u32(node, "max_maptrack_frames", &val) )
> +        if ( !val )
>          {
> -            if ( val > INT32_MAX )
> -                panic("max_maptrack_frames (%"PRIu32") overflow\n", val);
> -            d_cfg.max_maptrack_frames = val;
> +            /* Property found with no value, means max HW VL supported */
> +            ret = sve_domctl_vl_param(-1, &sve_vl_bits);
>          }
> -
> -        if ( dt_get_property(node, "sve", &val) )
> +        else
>          {
> -#ifdef CONFIG_ARM64_SVE
> -            unsigned int sve_vl_bits;
> -            bool ret = false;
> -
> -            if ( !val )
> -            {
> -                /* Property found with no value, means max HW VL supported */
> -                ret = sve_domctl_vl_param(-1, &sve_vl_bits);
> -            }
> +            if ( dt_property_read_u32(node, "sve", &val) )
> +                ret = sve_domctl_vl_param(val, &sve_vl_bits);
>              else
> -            {
> -                if ( dt_property_read_u32(node, "sve", &val) )
> -                    ret = sve_domctl_vl_param(val, &sve_vl_bits);
> -                else
> -                    panic("Error reading 'sve' property\n");
> -            }
> +                panic("Error reading 'sve' property\n");
> +        }
>  
> -            if ( ret )
> -                d_cfg.arch.sve_vl = sve_encode_vl(sve_vl_bits);
> -            else
> -                panic("SVE vector length error\n");
> +        if ( ret )
> +            d_cfg->arch.sve_vl = sve_encode_vl(sve_vl_bits);
> +        else
> +            panic("SVE vector length error\n");
>  #else
> -            panic("'sve' property found, but CONFIG_ARM64_SVE not 
> selected\n");
> +        panic("'sve' property found, but CONFIG_ARM64_SVE not selected\n");
>  #endif
> -        }
> -
> -        dt_property_read_string(node, "llc-colors", &llc_colors_str);
> -        if ( !llc_coloring_enabled && llc_colors_str )
> -            panic("'llc-colors' found, but LLC coloring is disabled\n");
> -
> -        /*
> -         * The variable max_init_domid is initialized with zero, so here it's
> -         * very important to use the pre-increment operator to call
> -         * domain_create() with a domid > 0. (domid == 0 is reserved for 
> Dom0)
> -         */
> -        d = domain_create(++max_init_domid, &d_cfg, flags);
> -        if ( IS_ERR(d) )
> -            panic("Error creating domain %s (rc = %ld)\n",
> -                  dt_node_name(node), PTR_ERR(d));
> -
> -        if ( llc_coloring_enabled &&
> -             (rc = domain_set_llc_colors_from_str(d, llc_colors_str)) )
> -            panic("Error initializing LLC coloring for domain %s (rc = 
> %d)\n",
> -                  dt_node_name(node), rc);
> -
> -        d->is_console = true;
> -        dt_device_set_used_by(node, d->domain_id);
> -
> -        rc = construct_domU(d, node);
> -        if ( rc )
> -            panic("Could not set up domain %s (rc = %d)\n",
> -                  dt_node_name(node), rc);
> -
> -        if ( d_cfg.flags & XEN_DOMCTL_CDF_xs_domain )
> -            set_xs_domain(d);
>      }
> -
> -    if ( need_xenstore && xs_domid == DOMID_INVALID )
> -        panic("xenstore requested, but xenstore domain not present\n");
> -
> -    initialize_domU_xenstore();
>  }
>  
>  /*
> diff --git a/xen/arch/arm/include/asm/Makefile 
> b/xen/arch/arm/include/asm/Makefile
> index 4a4036c951..831c914cce 100644
> --- a/xen/arch/arm/include/asm/Makefile
> +++ b/xen/arch/arm/include/asm/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  generic-y += altp2m.h
>  generic-y += device.h
> +generic-y += dom0less-build.h
>  generic-y += hardirq.h
>  generic-y += iocap.h
>  generic-y += paging.h
> diff --git a/xen/arch/arm/include/asm/dom0less-build.h 
> b/xen/arch/arm/include/asm/dom0less-build.h
> deleted file mode 100644
> index b0e41a1954..0000000000
> --- a/xen/arch/arm/include/asm/dom0less-build.h
> +++ /dev/null
> @@ -1,34 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0-only */
> -
> -#ifndef __ASM_DOM0LESS_BUILD_H_
> -#define __ASM_DOM0LESS_BUILD_H_
> -
> -#include <xen/stdbool.h>
> -
> -#ifdef CONFIG_DOM0LESS_BOOT
> -
> -void create_domUs(void);
> -bool is_dom0less_mode(void);
> -void set_xs_domain(struct domain *d);
> -
> -#else /* !CONFIG_DOM0LESS_BOOT */
> -
> -static inline void create_domUs(void) {}
> -static inline bool is_dom0less_mode(void)
> -{
> -    return false;
> -}
> -static inline void set_xs_domain(struct domain *d) {}
> -
> -#endif /* CONFIG_DOM0LESS_BOOT */
> -
> -#endif /* __ASM_DOM0LESS_BUILD_H_ */
> -
> -/*
> - * Local variables:
> - * mode: C
> - * c-file-style: "BSD"
> - * c-basic-offset: 4
> - * indent-tabs-mode: nil
> - * End:
> - */
> diff --git a/xen/common/Kconfig b/xen/common/Kconfig
> index be28060716..f291a5c1c7 100644
> --- a/xen/common/Kconfig
> +++ b/xen/common/Kconfig
> @@ -12,6 +12,15 @@ config CORE_PARKING
>       bool
>       depends on NR_CPUS > 1
>  
> +config DOM0LESS_BOOT
> +     bool "Dom0less boot support" if EXPERT
> +     depends on HAS_DOM0LESS && HAS_DEVICE_TREE
> +     default y
> +     help
> +       Dom0less boot support enables Xen to create and start domU guests 
> during
> +       Xen boot without the need of a control domain (Dom0), which could be
> +       present anyway.
> +
>  config GRANT_TABLE
>       bool "Grant table support" if EXPERT
>       default y
> @@ -74,6 +83,9 @@ config HAS_DEVICE_TREE
>       bool
>       select LIBFDT
>  
> +config HAS_DOM0LESS
> +     bool
> +
>  config HAS_DIT # Data Independent Timing
>       bool
>  
> diff --git a/xen/common/device-tree/Makefile b/xen/common/device-tree/Makefile
> index 7c549be38a..f3dafc9b81 100644
> --- a/xen/common/device-tree/Makefile
> +++ b/xen/common/device-tree/Makefile
> @@ -1,5 +1,6 @@
>  obj-y += bootfdt.init.o
>  obj-y += bootinfo.init.o
>  obj-y += device-tree.o
> +obj-$(CONFIG_DOM0LESS_BOOT) += dom0less-build.o
>  obj-$(CONFIG_OVERLAY_DTB) += dt-overlay.o
>  obj-y += intc.o
> diff --git a/xen/common/device-tree/dom0less-build.c 
> b/xen/common/device-tree/dom0less-build.c
> new file mode 100644
> index 0000000000..203b762e2c
> --- /dev/null
> +++ b/xen/common/device-tree/dom0less-build.c
> @@ -0,0 +1,294 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/bootfdt.h>
> +#include <xen/device_tree.h>
> +#include <xen/domain.h>
> +#include <xen/err.h>
> +#include <xen/event.h>
> +#include <xen/grant_table.h>
> +#include <xen/init.h>
> +#include <xen/iommu.h>
> +#include <xen/llc-coloring.h>
> +#include <xen/sched.h>
> +#include <xen/stdbool.h>
> +#include <xen/types.h>
> +
> +#include <public/bootfdt.h>
> +#include <public/domctl.h>
> +#include <public/event_channel.h>
> +
> +#include <asm/dom0less-build.h>
> +#include <asm/setup.h>
> +
> +static domid_t __initdata xs_domid = DOMID_INVALID;
> +
> +void __init set_xs_domain(struct domain *d)
> +{
> +    xs_domid = d->domain_id;
> +    set_global_virq_handler(d, VIRQ_DOM_EXC);
> +}
> +
> +bool __init is_dom0less_mode(void)
> +{
> +    struct bootmodules *mods = &bootinfo.modules;
> +    struct bootmodule *mod;
> +    unsigned int i;
> +    bool dom0found = false;
> +    bool domUfound = false;
> +
> +    /* Look into the bootmodules */
> +    for ( i = 0 ; i < mods->nr_mods ; i++ )
> +    {
> +        mod = &mods->module[i];
> +        /* Find if dom0 and domU kernels are present */
> +        if ( mod->kind == BOOTMOD_KERNEL )
> +        {
> +            if ( mod->domU == false )
> +            {
> +                dom0found = true;
> +                break;
> +            }
> +            else
> +                domUfound = true;
> +        }
> +    }
> +
> +    /*
> +     * If there is no dom0 kernel but at least one domU, then we are in
> +     * dom0less mode
> +     */
> +    return ( !dom0found && domUfound );
> +}
> +
> +static int __init alloc_xenstore_evtchn(struct domain *d)
> +{
> +    evtchn_alloc_unbound_t alloc;
> +    int rc;
> +
> +    alloc.dom = d->domain_id;
> +    alloc.remote_dom = xs_domid;
> +    rc = evtchn_alloc_unbound(&alloc, 0);
> +    if ( rc )
> +    {
> +        printk("Failed allocating event channel for domain\n");
> +        return rc;
> +    }
> +
> +    d->arch.hvm.params[HVM_PARAM_STORE_EVTCHN] = alloc.port;
> +
> +    return 0;
> +}
> +
> +static void __init initialize_domU_xenstore(void)
> +{
> +    struct domain *d;
> +
> +    if ( xs_domid == DOMID_INVALID )
> +        return;
> +
> +    for_each_domain( d )
> +    {
> +        uint64_t gfn = d->arch.hvm.params[HVM_PARAM_STORE_PFN];
> +        int rc;
> +
> +        if ( gfn == 0 )
> +            continue;
> +
> +        if ( is_xenstore_domain(d) )
> +            continue;
> +
> +        rc = alloc_xenstore_evtchn(d);
> +        if ( rc < 0 )
> +            panic("%pd: Failed to allocate xenstore_evtchn\n", d);
> +
> +        if ( gfn != XENSTORE_PFN_LATE_ALLOC && 
> IS_ENABLED(CONFIG_GRANT_TABLE) )
> +        {
> +            ASSERT(gfn < UINT32_MAX);
> +            gnttab_seed_entry(d, GNTTAB_RESERVED_XENSTORE, xs_domid, gfn);
> +        }
> +    }
> +}
> +
> +void __init create_domUs(void)
> +{
> +    struct dt_device_node *node;
> +    const char *dom0less_iommu;
> +    bool iommu = false;
> +    const struct dt_device_node *cpupool_node,
> +                                *chosen = dt_find_node_by_path("/chosen");
> +    const char *llc_colors_str = NULL;
> +
> +    BUG_ON(chosen == NULL);
> +    dt_for_each_child_node(chosen, node)
> +    {
> +        struct domain *d;
> +        struct xen_domctl_createdomain d_cfg = {0};
> +        unsigned int flags = 0U;
> +        bool has_dtb = false;
> +        uint32_t val;
> +        int rc;
> +
> +        if ( !dt_device_is_compatible(node, "xen,domain") )
> +            continue;
> +
> +        if ( (max_init_domid + 1) >= DOMID_FIRST_RESERVED )
> +            panic("No more domain IDs available\n");
> +
> +        d_cfg.max_evtchn_port = 1023;
> +        d_cfg.max_grant_frames = -1;
> +        d_cfg.max_maptrack_frames = -1;
> +        d_cfg.grant_opts = XEN_DOMCTL_GRANT_version(opt_gnttab_max_version);
> +
> +        if ( dt_property_read_u32(node, "capabilities", &val) )
> +        {
> +            if ( val & ~DOMAIN_CAPS_MASK )
> +                panic("Invalid capabilities (%"PRIx32")\n", val);
> +
> +            if ( val & DOMAIN_CAPS_CONTROL )
> +                flags |= CDF_privileged;
> +
> +            if ( val & DOMAIN_CAPS_HARDWARE )
> +            {
> +                if ( hardware_domain )
> +                    panic("Only 1 hardware domain can be specified! (%pd)\n",
> +                            hardware_domain);
> +
> +#ifdef CONFIG_GRANT_TABLE
> +                d_cfg.max_grant_frames = gnttab_dom0_frames();
> +#endif
> +                d_cfg.max_evtchn_port = -1;
> +                flags |= CDF_hardware;
> +                iommu = true;
> +            }
> +
> +            if ( val & DOMAIN_CAPS_XENSTORE )
> +            {
> +                if ( xs_domid != DOMID_INVALID )
> +                    panic("Only 1 xenstore domain can be specified! (%u)\n",
> +                            xs_domid);
> +
> +                d_cfg.flags |= XEN_DOMCTL_CDF_xs_domain;
> +                d_cfg.max_evtchn_port = -1;
> +            }
> +        }
> +
> +        if ( dt_find_property(node, "xen,static-mem", NULL) )
> +        {
> +            if ( llc_coloring_enabled )
> +                panic("LLC coloring and static memory are incompatible\n");
> +
> +            flags |= CDF_staticmem;
> +        }
> +
> +        if ( dt_property_read_bool(node, "direct-map") )
> +        {
> +            if ( !(flags & CDF_staticmem) )
> +                panic("direct-map is not valid for domain %s without static 
> allocation.\n",
> +                      dt_node_name(node));
> +
> +            flags |= CDF_directmap;
> +        }
> +
> +        if ( !dt_property_read_u32(node, "cpus", &d_cfg.max_vcpus) )
> +            panic("Missing property 'cpus' for domain %s\n",
> +                  dt_node_name(node));
> +
> +        if ( !dt_property_read_string(node, "passthrough", &dom0less_iommu) )
> +        {
> +            if ( flags & CDF_hardware )
> +                panic("Don't specify passthrough for hardware domain\n");
> +
> +            if ( !strcmp(dom0less_iommu, "enabled") )
> +                iommu = true;
> +        }
> +
> +        if ( (flags & CDF_hardware) && !(flags & CDF_directmap) &&
> +             !iommu_enabled )
> +            panic("non-direct mapped hardware domain requires iommu\n");
> +
> +        if ( dt_find_compatible_node(node, NULL, "multiboot,device-tree") )
> +        {
> +            if ( flags & CDF_hardware )
> +                panic("\"multiboot,device-tree\" incompatible with hardware 
> domain\n");
> +
> +            has_dtb = true;
> +        }
> +
> +        if ( iommu_enabled && (iommu || has_dtb) )
> +            d_cfg.flags |= XEN_DOMCTL_CDF_iommu;
> +
> +        /* Get the optional property domain-cpupool */
> +        cpupool_node = dt_parse_phandle(node, "domain-cpupool", 0);
> +        if ( cpupool_node )
> +        {
> +            int pool_id = btcpupools_get_domain_pool_id(cpupool_node);
> +            if ( pool_id < 0 )
> +                panic("Error getting cpupool id from domain-cpupool (%d)\n",
> +                      pool_id);
> +            d_cfg.cpupool_id = pool_id;
> +        }
> +
> +        if ( dt_property_read_u32(node, "max_grant_version", &val) )
> +            d_cfg.grant_opts = XEN_DOMCTL_GRANT_version(val);
> +
> +        if ( dt_property_read_u32(node, "max_grant_frames", &val) )
> +        {
> +            if ( val > INT32_MAX )
> +                panic("max_grant_frames (%"PRIu32") overflow\n", val);
> +            d_cfg.max_grant_frames = val;
> +        }
> +
> +        if ( dt_property_read_u32(node, "max_maptrack_frames", &val) )
> +        {
> +            if ( val > INT32_MAX )
> +                panic("max_maptrack_frames (%"PRIu32") overflow\n", val);
> +            d_cfg.max_maptrack_frames = val;
> +        }
> +
> +        dt_property_read_string(node, "llc-colors", &llc_colors_str);
> +        if ( !llc_coloring_enabled && llc_colors_str )
> +            panic("'llc-colors' found, but LLC coloring is disabled\n");
> +
> +        arch_create_domUs(node, &d_cfg, flags);
> +
> +        /*
> +         * The variable max_init_domid is initialized with zero, so here it's
> +         * very important to use the pre-increment operator to call
> +         * domain_create() with a domid > 0. (domid == 0 is reserved for 
> Dom0)
> +         */
> +        d = domain_create(++max_init_domid, &d_cfg, flags);
> +        if ( IS_ERR(d) )
> +            panic("Error creating domain %s (rc = %ld)\n",
> +                  dt_node_name(node), PTR_ERR(d));
> +
> +        if ( llc_coloring_enabled &&
> +             (rc = domain_set_llc_colors_from_str(d, llc_colors_str)) )
> +            panic("Error initializing LLC coloring for domain %s (rc = 
> %d)\n",
> +                  dt_node_name(node), rc);
> +
> +        d->is_console = true;
> +        dt_device_set_used_by(node, d->domain_id);
> +
> +        rc = construct_domU(d, node);
> +        if ( rc )
> +            panic("Could not set up domain %s (rc = %d)\n",
> +                  dt_node_name(node), rc);
> +
> +        if ( d_cfg.flags & XEN_DOMCTL_CDF_xs_domain )
> +            set_xs_domain(d);
> +    }
> +
> +    if ( need_xenstore && xs_domid == DOMID_INVALID )
> +        panic("xenstore requested, but xenstore domain not present\n");
> +
> +    initialize_domU_xenstore();
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/include/asm-generic/dom0less-build.h 
> b/xen/include/asm-generic/dom0less-build.h
> new file mode 100644
> index 0000000000..ef2073d802
> --- /dev/null
> +++ b/xen/include/asm-generic/dom0less-build.h
> @@ -0,0 +1,50 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#ifndef __ASM_GENERIC_DOM0LESS_BUILD_H__
> +#define __ASM_GENERIC_DOM0LESS_BUILD_H__
> +
> +#include <xen/stdbool.h>
> +
> +struct domain;
> +
> +#ifdef CONFIG_DOM0LESS_BOOT
> +
> +#include <public/domctl.h>
> +
> +struct dt_device_node;
> +
> +/* TODO: remove both when construct_domU() will be moved to common. */
> +#define XENSTORE_PFN_LATE_ALLOC UINT64_MAX
> +extern bool need_xenstore;
> +
> +void create_domUs(void);
> +bool is_dom0less_mode(void);
> +void set_xs_domain(struct domain *d);
> +
> +int construct_domU(struct domain *d, const struct dt_device_node *node);
> +
> +void arch_create_domUs(struct dt_device_node *node,
> +                       struct xen_domctl_createdomain *d_cfg,
> +                       unsigned int flags);
> +
> +#else /* !CONFIG_DOM0LESS_BOOT */
> +
> +static inline void create_domUs(void) {}
> +static inline bool is_dom0less_mode(void)
> +{
> +    return false;
> +}
> +static inline void set_xs_domain(struct domain *d) {}
> +
> +#endif /* CONFIG_DOM0LESS_BOOT */
> +
> +#endif /* __ASM_GENERIC_DOM0LESS_BUILD_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> -- 
> 2.49.0
> 



 


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