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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v4 07/13] x86/hyperlaunch: obtain cmdline from device tree
On Thu, Apr 17, 2025 at 01:48:29PM +0100, Alejandro Vallejo wrote:
> From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
>
> Add support to read the command line from the hyperlauunch device tree.
> The device tree command line is located in the "bootargs" property of the
> "multiboot,kernel" node.
>
> A boot loader command line, e.g. a grub module string field, takes
> precendence ove the device tree one since it is easier to modify.
^^ over
Also, I would explain the command line parsing rules in the code commentary for
domain_cmdline_size() below.
>
> Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> Signed-off-by: Alejandro Vallejo <agarciav@xxxxxxx>
> ---
> v4:
> * Removed __init from header declarations.
> * Removed ifdef guards, as DCE ensures the missing definitions don't
> matter.
> * Removed ifdef guards from new helpers in domain-builder/fdt.c
> * Rely on DCE instead.
> * Restored checks for cmdline_pa being zero.
> * swapped offset and poffset varnames in libfdt-xen.h helper.
> * swapped name and pname varnames in libfdt-xen.h helper.
> * Turned foo == 0 into !foo in libfdt-xen.h helper.
> ---
> xen/arch/x86/include/asm/bootinfo.h | 6 ++++--
> xen/arch/x86/setup.c | 10 +++++++--
> xen/common/domain-builder/core.c | 32 +++++++++++++++++++++++++++++
> xen/common/domain-builder/fdt.c | 6 ++++++
> xen/common/domain-builder/fdt.h | 24 ++++++++++++++++++++++
> xen/include/xen/domain-builder.h | 4 ++++
> xen/include/xen/libfdt/libfdt-xen.h | 23 +++++++++++++++++++++
> 7 files changed, 101 insertions(+), 4 deletions(-)
>
> diff --git a/xen/arch/x86/include/asm/bootinfo.h
> b/xen/arch/x86/include/asm/bootinfo.h
> index 1e3d582e45..5b2c93b1ef 100644
> --- a/xen/arch/x86/include/asm/bootinfo.h
> +++ b/xen/arch/x86/include/asm/bootinfo.h
> @@ -35,11 +35,13 @@ struct boot_module {
>
> /*
> * Module State Flags:
> - * relocated: indicates module has been relocated in memory.
> - * released: indicates module's pages have been freed.
> + * relocated: indicates module has been relocated in memory.
> + * released: indicates module's pages have been freed.
> + * fdt_cmdline: indicates module's cmdline is in the FDT.
> */
> bool relocated:1;
> bool released:1;
> + bool fdt_cmdline:1;
>
> /*
> * A boot module may need decompressing by Xen. Headroom is an estimate
> of
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 4f669f3c60..4cae13163b 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -984,7 +984,10 @@ static size_t __init domain_cmdline_size(const struct
> boot_info *bi,
> {
> size_t s = bi->kextra ? strlen(bi->kextra) : 0;
>
> - s += bd->kernel->cmdline_pa ? strlen(__va(bd->kernel->cmdline_pa)) : 0;
> + if ( bd->kernel->fdt_cmdline )
> + s += builder_get_cmdline_size(bi, bd->kernel->cmdline_pa);
> + else if ( bd->kernel->cmdline_pa )
> + s += strlen(__va(bd->kernel->cmdline_pa));
>
> if ( s == 0 )
> return s;
> @@ -1047,7 +1050,10 @@ static struct domain *__init create_dom0(struct
> boot_info *bi)
> if ( !(cmdline = xzalloc_array(char, cmdline_size)) )
> panic("Error allocating cmdline buffer for %pd\n", d);
>
> - if ( bd->kernel->cmdline_pa )
> + if ( bd->kernel->fdt_cmdline )
> + builder_get_cmdline(
> + bi, bd->kernel->cmdline_pa, cmdline, cmdline_size);
> + else if ( bd->kernel->cmdline_pa )
> strlcpy(cmdline,
> cmdline_cook(__va(bd->kernel->cmdline_pa), bi->loader),
> cmdline_size);
> diff --git a/xen/common/domain-builder/core.c
> b/xen/common/domain-builder/core.c
> index 924cb495a3..4b4230f2ff 100644
> --- a/xen/common/domain-builder/core.c
> +++ b/xen/common/domain-builder/core.c
> @@ -8,9 +8,41 @@
> #include <xen/lib.h>
>
> #include <asm/bootinfo.h>
> +#include <asm/setup.h>
>
> #include "fdt.h"
>
> +size_t __init builder_get_cmdline_size(struct boot_info *bi, int offset)
> +{
> + const void *fdt;
> + int size;
> +
> + if ( !IS_ENABLED(CONFIG_DOMAIN_BUILDER) )
> + return 0;
> +
> + fdt = bootstrap_map_bm(&bi->mods[HYPERLAUNCH_MODULE_IDX]);
> + size = fdt_cmdline_prop_size(fdt, offset);
> + bootstrap_unmap();
> +
> + return max(0, size);
> +}
> +
> +int __init builder_get_cmdline(
> + struct boot_info *bi, int offset, char *cmdline, size_t size)
> +{
> + const void *fdt;
> + int ret;
> +
> + if ( !IS_ENABLED(CONFIG_DOMAIN_BUILDER) )
> + return 0;
> +
> + fdt = bootstrap_map_bm(&bi->mods[HYPERLAUNCH_MODULE_IDX]);
> + ret = fdt_cmdline_prop_copy(fdt, offset, cmdline, size);
> + bootstrap_unmap();
> +
> + return ret;
> +}
> +
> void __init builder_init(struct boot_info *bi)
> {
> bi->hyperlaunch_enabled = false;
> diff --git a/xen/common/domain-builder/fdt.c b/xen/common/domain-builder/fdt.c
> index 1fae6add3b..50fde2d007 100644
> --- a/xen/common/domain-builder/fdt.c
> +++ b/xen/common/domain-builder/fdt.c
> @@ -209,6 +209,12 @@ static int __init process_domain_node(
> printk(XENLOG_INFO " kernel: multiboot-index=%d\n", idx);
> bi->mods[idx].type = BOOTMOD_KERNEL;
> bd->kernel = &bi->mods[idx];
> +
> + /* If bootloader didn't set cmdline, see if FDT provides one. */
> + if ( bd->kernel->cmdline_pa &&
> + !((char *)__va(bd->kernel->cmdline_pa))[0] )
> + bd->kernel->fdt_cmdline = fdt_get_prop_offset(
> + fdt, node, "bootargs", &bd->kernel->cmdline_pa);
> }
> }
>
> diff --git a/xen/common/domain-builder/fdt.h b/xen/common/domain-builder/fdt.h
> index 8c98a256eb..d2ae7d5c36 100644
> --- a/xen/common/domain-builder/fdt.h
> +++ b/xen/common/domain-builder/fdt.h
> @@ -9,6 +9,30 @@ struct boot_info;
> /* hyperlaunch fdt is required to be module 0 */
> #define HYPERLAUNCH_MODULE_IDX 0
>
> +static inline int __init fdt_cmdline_prop_size(const void *fdt, int offset)
> +{
> + int ret;
> +
> + fdt_get_property_by_offset(fdt, offset, &ret);
Perhaps something like
(void)fdt_get_property_by_offset...
since there's no need to check the return value?
> +
> + return ret;
> +}
> +
> +static inline int __init fdt_cmdline_prop_copy(
> + const void *fdt, int offset, char *cmdline, size_t size)
> +{
> + int ret;
> + const struct fdt_property *prop =
> + fdt_get_property_by_offset(fdt, offset, &ret);
> +
> + if ( ret < 0 )
> + return ret;
> +
> + ASSERT(size > ret);
> +
> + return strlcpy(cmdline, prop->data, ret);
> +}
> +
> int has_hyperlaunch_fdt(const struct boot_info *bi);
> int walk_hyperlaunch_fdt(struct boot_info *bi);
>
> diff --git a/xen/include/xen/domain-builder.h
> b/xen/include/xen/domain-builder.h
> index ac2b84775d..ac0fd8f60b 100644
> --- a/xen/include/xen/domain-builder.h
> +++ b/xen/include/xen/domain-builder.h
> @@ -4,6 +4,10 @@
>
> struct boot_info;
>
> +size_t builder_get_cmdline_size(const struct boot_info *bi, int offset);
> +int builder_get_cmdline(const struct boot_info *bi, int offset,
> + char *cmdline, size_t size);
> +
> void builder_init(struct boot_info *bi);
>
> #endif /* __XEN_DOMAIN_BUILDER_H__ */
> diff --git a/xen/include/xen/libfdt/libfdt-xen.h
> b/xen/include/xen/libfdt/libfdt-xen.h
> index deafb25d98..afc76e7750 100644
> --- a/xen/include/xen/libfdt/libfdt-xen.h
> +++ b/xen/include/xen/libfdt/libfdt-xen.h
> @@ -24,6 +24,29 @@ static inline int __init fdt_prop_as_u32(
> return 0;
> }
>
> +static inline bool __init fdt_get_prop_offset(
> + const void *fdt, int node, const char *pname, unsigned long *poffset)
> +{
> + int ret, offset;
> + const char *name;
> +
> + fdt_for_each_property_offset(offset, fdt, node)
> + {
> + fdt_getprop_by_offset(fdt, offset, &name, &ret);
Add
(void)fdt_get_property_by_offset...
here as well?
> +
> + if ( ret < 0 )
> + continue;
> +
> + if ( !strcmp(name, pname) )
> + {
> + *poffset = offset;
> + return true;
> + }
> + }
> +
> + return false;
> +}
> +
> static inline int fdt_get_mem_rsv_paddr(const void *fdt, int n,
> paddr_t *address,
> paddr_t *size)
> --
> 2.43.0
>
>
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