Re: [kvm-unit-tests PATCH v5 11/29] arm64: Add support for setting up the PSCI conduit through ACPI

[Shaoqin Huang <shahuang@redhat.com>]

On 4/28/23 20:03, Nikos Nikoleris wrote:
> In systems with ACPI support and when a DT is not provided, we can use
> the FADT to discover whether PSCI calls need to use smc or hvc
> calls. This change implements this but retains the default behavior;
> we check if a valid DT is provided, if not, we try to setup the PSCI
> conduit using ACPI.
> 
> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> ---
>   arm/Makefile.arm64 |  4 ++++
>   lib/acpi.h         |  5 +++++
>   lib/arm/psci.c     | 37 ++++++++++++++++++++++++++++++++++++-
>   3 files changed, 45 insertions(+), 1 deletion(-)
> 
> diff --git a/arm/Makefile.arm64 b/arm/Makefile.arm64
> index 42e18e77..6dff6cad 100644
> --- a/arm/Makefile.arm64
> +++ b/arm/Makefile.arm64
> @@ -25,6 +25,10 @@ cflatobjs += lib/arm64/processor.o
>   cflatobjs += lib/arm64/spinlock.o
>   cflatobjs += lib/arm64/gic-v3-its.o lib/arm64/gic-v3-its-cmd.o
>   
> +ifeq ($(CONFIG_EFI),y)
> +cflatobjs += lib/acpi.o
> +endif
> +
>   OBJDIRS += lib/arm64
>   
>   # arm64 specific tests
> diff --git a/lib/acpi.h b/lib/acpi.h
> index b714677e..ef4a8e1d 100644
> --- a/lib/acpi.h
> +++ b/lib/acpi.h
> @@ -129,6 +129,11 @@ struct acpi_table_fadt {
>   	u64 hypervisor_id;	/* Hypervisor Vendor ID (ACPI 6.0) */
>   };
>   
> +/* Masks for FADT ARM Boot Architecture Flags (arm_boot_flags) ACPI 5.1 */
> +
> +#define ACPI_FADT_PSCI_COMPLIANT    (1)	/* 00: [V5+] PSCI 0.2+ is implemented */
> +#define ACPI_FADT_PSCI_USE_HVC      (1<<1)	/* 01: [V5+] HVC must be used instead of SMC as the PSCI conduit */
> +
>   struct acpi_table_facs_rev1 {
>   	u32 signature;		/* ACPI Signature */
>   	u32 length;		/* Length of structure, in bytes */
> diff --git a/lib/arm/psci.c b/lib/arm/psci.c
> index 9c031a12..bddb0787 100644
> --- a/lib/arm/psci.c
> +++ b/lib/arm/psci.c
> @@ -56,7 +56,7 @@ void psci_system_off(void)
>   	printf("CPU%d unable to do system off (error = %d)\n", smp_processor_id(), err);
>   }
>   
> -void psci_set_conduit(void)
> +static void psci_set_conduit_fdt(void)
>   {
>   	const void *fdt = dt_fdt();
>   	const struct fdt_property *method;
> @@ -75,3 +75,38 @@ void psci_set_conduit(void)
>   	else
>   		assert_msg(false, "Unknown PSCI conduit: %s", method->data);
>   }
> +
> +#ifdef CONFIG_EFI
> +
> +#include <acpi.h>
> +
> +static void psci_set_conduit_acpi(void)
> +{
> +	struct acpi_table_fadt *fadt = find_acpi_table_addr(FACP_SIGNATURE);
> +
> +	assert_msg(fadt, "Unable to find ACPI FADT");
> +	assert_msg(fadt->arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT,
> +		   "PSCI is not supported in this platform");
> +
> +	if (fadt->arm_boot_flags & ACPI_FADT_PSCI_USE_HVC)
> +		psci_invoke = psci_invoke_hvc;
> +	else
> +		psci_invoke = psci_invoke_smc;
> +}
> +
> +#else
> +
> +static void psci_set_conduit_acpi(void)
> +{
> +	assert_msg(false, "ACPI not available");
> +}
> +
> +#endif
> +
> +void psci_set_conduit(void)
> +{
> +	if (dt_available())
> +		psci_set_conduit_fdt();
> +	else
> +		psci_set_conduit_acpi();
> +}

-- 
Shaoqin