Re: [PATCH v5 08/12] xen/arm: Implement PSCI SYSTEM_SUSPEND call (host interface)

[Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>]

Hi Mykola,

Sequence of next 3 patches (and previous one) really puzzles me. Can you
first implement hyp_resume() function, then add PSCI_SYSTEM_SUSPEND call
and only then implement system_suspend() function? Why do this backwards?

Mykola Kvach <xakep.amatop@gmail.com> writes:

> From: Mirela Simonovic <mirela.simonovic@aggios.com>
>
> Invoke PSCI SYSTEM_SUSPEND to finalize Xen's suspend sequence on ARM64 platforms.
> Pass the resume entry point (hyp_resume) as the first argument to EL3. The resume
> handler is currently a stub and will be implemented later in assembly. Ignore the
> context ID argument, as is done in Linux.
>
> Only enable this path when CONFIG_SYSTEM_SUSPEND is set and
> PSCI version is >= 1.0.
>
> Signed-off-by: Mirela Simonovic <mirela.simonovic@aggios.com>
> Signed-off-by: Saeed Nowshadi <saeed.nowshadi@xilinx.com>
> Signed-off-by: Mykyta Poturai <mykyta_poturai@epam.com>
> Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>
> ---
> Changes in v4:
>   - select the appropriate PSCI SYSTEM_SUSPEND function ID based on platform
>   - update comments and commit message to reflect recent changes
>
> Changes in v3:
>   - return PSCI_NOT_SUPPORTED instead of a hardcoded 1 on ARM32
>   - check PSCI version before invoking SYSTEM_SUSPEND in call_psci_system_suspend
> ---
>  xen/arch/arm/arm64/head.S          |  8 ++++++++
>  xen/arch/arm/include/asm/psci.h    |  1 +
>  xen/arch/arm/include/asm/suspend.h |  2 ++
>  xen/arch/arm/psci.c                | 23 ++++++++++++++++++++++-
>  xen/arch/arm/suspend.c             |  5 +++++
>  5 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index 72c7b24498..3522c497c5 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -561,6 +561,14 @@ END(efi_xen_start)
>  
>  #endif /* CONFIG_ARM_EFI */
>  
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +
> +FUNC(hyp_resume)
> +        b .
> +END(hyp_resume)
> +
> +#endif /* CONFIG_SYSTEM_SUSPEND */
> +
>  /*
>   * Local variables:
>   * mode: ASM
> diff --git a/xen/arch/arm/include/asm/psci.h b/xen/arch/arm/include/asm/psci.h
> index 48a93e6b79..bb3c73496e 100644
> --- a/xen/arch/arm/include/asm/psci.h
> +++ b/xen/arch/arm/include/asm/psci.h
> @@ -23,6 +23,7 @@ int call_psci_cpu_on(int cpu);
>  void call_psci_cpu_off(void);
>  void call_psci_system_off(void);
>  void call_psci_system_reset(void);
> +int call_psci_system_suspend(void);
>  
>  /* Range of allocated PSCI function numbers */
>  #define	PSCI_FNUM_MIN_VALUE                 _AC(0,U)
> diff --git a/xen/arch/arm/include/asm/suspend.h b/xen/arch/arm/include/asm/suspend.h
> index 78d0e2383b..55041a5d06 100644
> --- a/xen/arch/arm/include/asm/suspend.h
> +++ b/xen/arch/arm/include/asm/suspend.h
> @@ -7,6 +7,8 @@
>  
>  int host_system_suspend(void);
>  
> +void hyp_resume(void);
> +
>  #endif /* CONFIG_SYSTEM_SUSPEND */
>  
>  #endif /* __ASM_ARM_SUSPEND_H__ */
> diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
> index b6860a7760..c9d126b195 100644
> --- a/xen/arch/arm/psci.c
> +++ b/xen/arch/arm/psci.c
> @@ -17,17 +17,20 @@
>  #include <asm/cpufeature.h>
>  #include <asm/psci.h>
>  #include <asm/acpi.h>
> +#include <asm/suspend.h>
>  
>  /*
>   * While a 64-bit OS can make calls with SMC32 calling conventions, for
>   * some calls it is necessary to use SMC64 to pass or return 64-bit values.
> - * For such calls PSCI_0_2_FN_NATIVE(x) will choose the appropriate
> + * For such calls PSCI_*_FN_NATIVE(x) will choose the appropriate
>   * (native-width) function ID.
>   */
>  #ifdef CONFIG_ARM_64
>  #define PSCI_0_2_FN_NATIVE(name)    PSCI_0_2_FN64_##name
> +#define PSCI_1_0_FN_NATIVE(name)    PSCI_1_0_FN64_##name
>  #else
>  #define PSCI_0_2_FN_NATIVE(name)    PSCI_0_2_FN32_##name
> +#define PSCI_1_0_FN_NATIVE(name)    PSCI_1_0_FN32_##name
>  #endif
>  
>  uint32_t psci_ver;
> @@ -60,6 +63,24 @@ void call_psci_cpu_off(void)
>      }
>  }
>  
> +int call_psci_system_suspend(void)
> +{
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    struct arm_smccc_res res;
> +
> +    if ( psci_ver < PSCI_VERSION(1, 0) )
> +        return PSCI_NOT_SUPPORTED;
> +
> +    /* 2nd argument (context ID) is not used */
> +    arm_smccc_smc(PSCI_1_0_FN_NATIVE(SYSTEM_SUSPEND), __pa(hyp_resume), &res);
> +    return PSCI_RET(res);
> +#else
> +    dprintk(XENLOG_WARNING,
> +            "SYSTEM_SUSPEND not supported (CONFIG_SYSTEM_SUSPEND disabled)\n");
> +    return PSCI_NOT_SUPPORTED;
> +#endif
> +}
> +
>  void call_psci_system_off(void)
>  {
>      if ( psci_ver > PSCI_VERSION(0, 1) )
> diff --git a/xen/arch/arm/suspend.c b/xen/arch/arm/suspend.c
> index abf4b928ce..11e86b7f51 100644
> --- a/xen/arch/arm/suspend.c
> +++ b/xen/arch/arm/suspend.c
> @@ -1,5 +1,6 @@
>  /* SPDX-License-Identifier: GPL-2.0-only */
>  
> +#include <asm/psci.h>
>  #include <xen/console.h>
>  #include <xen/cpu.h>
>  #include <xen/llc-coloring.h>
> @@ -70,6 +71,10 @@ static long system_suspend(void *data)
>       */
>      update_boot_mapping(true);
>  
> +    status = call_psci_system_suspend();
> +    if ( status )
> +        dprintk(XENLOG_WARNING, "PSCI system suspend failed, err=%d\n", status);

So this is where missing call to PSCI_SYSTEM_SUSPEND is... 

> +
>      system_state = SYS_STATE_resume;
>      update_boot_mapping(false);

-- 
WBR, Volodymyr