Re: [PATCH 1/2] Create UV efi_call macros

Matt Fleming
2016-05-12T12:06:00Z

(Adding author of arch_efi_call code)

On Wed, 11 May, at 02:55:44PM, Alex Thorlton wrote:
> We need a slightly different macro than the standard efi_call_virt,
> since those macros all assume that the function pointer, f, that gets
> passed in will live somewhere in efi.systab->runtime. Our EFI function
> pointer lives in efi.uv_systab, so we can't use the standard macros out
> of the box.

Is that true of all EFI services pointers? From reading the SGI/UV
code I got the impression that it's possible to call the standard
services via efi.systab->runtime but you also need the ability to call
these UV bios functions, which are not accessible via efi.systab.

Do you actually want the same environment setup and teardown to happen
when calling efi.uv_systab ? Or are you simply trying to reuse the
efi_call() implementation?

> This commit creates some new uv_* macros that are functionally
> equivalent to the standard ones, with the exception of allowing us to
> use a different function pointer. I figure that we won't want to call
> these uv_* in the end (we'll probably want something more generic), but
> I thought I would get everyone's thoughts on how we might best reach
> that goal instead of just trying to come up with a new implementation on
> my own.
>
> By itself, this commit does get our machines booting, but it needs the
> small fix to the efi_call assembly code for our modules to work.

Could you provide some more details in the changelog on why your
machine doesn't boot without this change?

> Signed-off-by: Alex Thorlton <athorlton@sgi.com>
> Cc: Dimitri Sivanich <sivanich@sgi.com>
> Cc: Russ Anderson <rja@sgi.com>
> Cc: Mike Travis <travis@sgi.com>
> Cc: Matt Fleming <matt@codeblueprint.co.uk>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> Cc: linux-efi@vger.kernel.org
> ---
> arch/x86/include/asm/efi.h | 3 ++
> arch/x86/platform/uv/bios_uv.c | 3 +-
> drivers/firmware/efi/runtime-wrappers.c | 44 +-------------------------
> include/linux/efi.h | 55 +++++++++++++++++++++++++++++++++
> 4 files changed, 60 insertions(+), 45 deletions(-)
>
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index 78d1e74..f384047 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -84,6 +84,9 @@ struct efi_scratch {
> #define arch_efi_call_virt(f, args...) \
> efi_call((void *)efi.systab->runtime->f, args) \
>
> +#define uv_efi_call_virt(f, args...) \
> + efi_call((void *)f, args) \
> +
> #define arch_efi_call_virt_teardown() \
> ({ \
> if (efi_scratch.use_pgd) { \
> diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c
> index 815fec6..62a46cb 100644
> --- a/arch/x86/platform/uv/bios_uv.c
> +++ b/arch/x86/platform/uv/bios_uv.c
> @@ -40,8 +40,7 @@ s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
> */
> return BIOS_STATUS_UNIMPLEMENTED;
>
> - ret = efi_call((void *)__va(tab->function), (u64)which,
> - a1, a2, a3, a4, a5);
> + ret = uv_call_virt(tab->function, (u64)which, a1, a2, a3, a4, a5);
> return ret;
> }
> EXPORT_SYMBOL_GPL(uv_bios_call);
> diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
> index 23bef6b..008a1a3 100644
> --- a/drivers/firmware/efi/runtime-wrappers.c
> +++ b/drivers/firmware/efi/runtime-wrappers.c
> @@ -22,7 +22,7 @@
> #include <linux/stringify.h>
> #include <asm/efi.h>
>
> -static void efi_call_virt_check_flags(unsigned long flags, const char *call)
> +void efi_call_virt_check_flags(unsigned long flags, const char *call)
> {
> unsigned long cur_flags, mismatch;
>
> @@ -39,48 +39,6 @@ static void efi_call_virt_check_flags(unsigned long flags, const char *call)
> }
>
> /*
> - * Arch code can implement the following three template macros, avoiding
> - * reptition for the void/non-void return cases of {__,}efi_call_virt:
> - *
> - * * arch_efi_call_virt_setup
> - *
> - * Sets up the environment for the call (e.g. switching page tables,
> - * allowing kernel-mode use of floating point, if required).
> - *
> - * * arch_efi_call_virt
> - *
> - * Performs the call. The last expression in the macro must be the call
> - * itself, allowing the logic to be shared by the void and non-void
> - * cases.
> - *
> - * * arch_efi_call_virt_teardown
> - *
> - * Restores the usual kernel environment once the call has returned.
> - */
> -
> -#define efi_call_virt(f, args...) \
> -({ \
> - efi_status_t __s; \
> - unsigned long flags; \
> - arch_efi_call_virt_setup(); \
> - local_save_flags(flags); \
> - __s = arch_efi_call_virt(f, args); \
> - efi_call_virt_check_flags(flags, __stringify(f)); \
> - arch_efi_call_virt_teardown(); \
> - __s; \
> -})
> -
> -#define __efi_call_virt(f, args...) \
> -({ \
> - unsigned long flags; \
> - arch_efi_call_virt_setup(); \
> - local_save_flags(flags); \
> - arch_efi_call_virt(f, args); \
> - efi_call_virt_check_flags(flags, __stringify(f)); \
> - arch_efi_call_virt_teardown(); \
> -})
> -
> -/*
> * According to section 7.1 of the UEFI spec, Runtime Services are not fully
> * reentrant, and there are particular combinations of calls that need to be
> * serialized. (source: UEFI Specification v2.4A)
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index df7acb5..f429269 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -1471,4 +1471,59 @@ efi_status_t efi_setup_gop(efi_system_table_t *sys_table_arg,
> unsigned long size);
>
> bool efi_runtime_disabled(void);
> +extern void efi_call_virt_check_flags(unsigned long flags, const char *call);
> +
> +/*
> + * Arch code can implement the following three template macros, avoiding
> + * reptition for the void/non-void return cases of {__,}efi_call_virt:
> + *
> + * * arch_efi_call_virt_setup
> + *
> + * Sets up the environment for the call (e.g. switching page tables,
> + * allowing kernel-mode use of floating point, if required).
> + *
> + * * arch_efi_call_virt
> + *
> + * Performs the call. The last expression in the macro must be the call
> + * itself, allowing the logic to be shared by the void and non-void
> + * cases.
> + *
> + * * arch_efi_call_virt_teardown
> + *
> + * Restores the usual kernel environment once the call has returned.
> + */
> +
> +#define efi_call_virt(f, args...) \
> +({ \
> + efi_status_t __s; \
> + unsigned long flags; \
> + arch_efi_call_virt_setup(); \
> + local_save_flags(flags); \
> + __s = arch_efi_call_virt(f, args); \
> + efi_call_virt_check_flags(flags, __stringify(f)); \
> + arch_efi_call_virt_teardown(); \
> + __s; \
> +})
> +
> +#define __efi_call_virt(f, args...) \
> +({ \
> + unsigned long flags; \
> + arch_efi_call_virt_setup(); \
> + local_save_flags(flags); \
> + arch_efi_call_virt(f, args); \
> + efi_call_virt_check_flags(flags, __stringify(f)); \
> + arch_efi_call_virt_teardown(); \
> +})
> +
> +#define uv_call_virt(f, args...) \
> +({ \
> + efi_status_t __s; \
> + unsigned long flags; \
> + arch_efi_call_virt_setup(); \
> + local_save_flags(flags); \
> + __s = uv_efi_call_virt(f, args); \
> + efi_call_virt_check_flags(flags, __stringify(f)); \
> + arch_efi_call_virt_teardown(); \
> + __s; \
> +})
> #endif /* _LINUX_EFI_H */
> --
> 1.8.5.6
>