Re: [PATCH 3/4] ArmVirtPkg/PlatformPeiLib: implement Reset2 PPI based on PSCI

["Laszlo Ersek" <lersek@redhat.com>]

On 01/07/20 10:47, Ard Biesheuvel wrote:
> Extend the existing DT traversal routine in PlatformPeiLib with
> discovery of the PSCI method, and expose an implementation of the
> Reset2 PPI based on the method found.
> 
> This satisfies a dependency of Tcg2Pei, which needs to reset the
> platform in some cases. Since there are no other uses for system
> reset in PEI on ArmVirtQemu, simply expose the PPI directly rather
> than using the generic ResetSystemPei and the associated plumbing.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf |   3 +
>  ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c   | 123 ++++++++++++++++++++
>  2 files changed, 126 insertions(+)

Tcg2Pei uses ResetCold() from ResetSystemLib.

ArmVirtPkg's existent ResetSystemLib instance
(ArmVirtPsciResetSystemLib/ArmVirtPsciResetSystemLib.inf) is only
suitable for DXE_DRIVER and DXE_RUNTIME_DRIVER instances. It uses our
FDT Client protocol for looking up (I think) more or less the same
things that you parse here.

As a PEI phase replacement, this patch produces gEfiPeiReset2PpiGuid,
and then in patch#4, we resolve ResetSystemLib, for PEIMs, to the

  MdeModulePkg/Library/PeiResetSystemLib/PeiResetSystemLib.inf

instance, which depends on the PPI installed here.

I'm not too happy about installing the gEfiPeiReset2PpiGuid from
PlatformPeiLib.

As replacement, it's not ResetSystemPei what I'd recommend (which
depends on a PEI-phase ResetSystemLib instance anyway, which we don't
have, in the first place).

(1) Instead, I'd recommend implementing a PEI-phase ResetSystemLib for
ArmVirtQemu. (Under ArmVirtPkg/Library/ArmVirtPsciResetSystemLib -- new
INF file.)

Would that be a large burden? I think we'd need a helper function in
that lib instance, for returning HVC versus SMC (from the FDT), and then
we'd have to call the proper interface for the actual reset. Not fast,
but resets don't need to be fast I think.

BTW I think the following modules are never meant to be used together:

  MdeModulePkg/Library/PeiResetSystemLib/PeiResetSystemLib.inf
  MdeModulePkg/Universal/ResetSystemPei/ResetSystemPei.inf

because they seem to depend mutually on each other's abstract interface
(PPI vs. lib class). So I think a given platform should include *at most
one* of these, on top of the "other" facility that it already exposes.
In ArmVirtQemu's case, I'd suggest implementing the lib class for PEI,
and then we can include "ResetSystemPei" whenever the need arises.

Thanks,
Laszlo

> 
> diff --git a/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf b/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
> index c41ee22c9767..72ed2413a768 100644
> --- a/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
> +++ b/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
> @@ -28,6 +28,8 @@ [Packages]
>    SecurityPkg/SecurityPkg.dec
>  
>  [LibraryClasses]
> +  ArmSmcLib
> +  ArmHvcLib
>    DebugLib
>    HobLib
>    FdtLib
> @@ -44,6 +46,7 @@ [Pcd]
>    gEfiSecurityPkgTokenSpaceGuid.PcdTpmBaseAddress         ## SOMETIMES_PRODUCES
>  
>  [Ppis]
> +  gEfiPeiReset2PpiGuid                                    ## SOMETIMES_PRODUCES
>    gOvmfTpmDiscoveredPpiGuid                               ## SOMETIMES_PRODUCES
>  
>  [Guids]
> diff --git a/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c b/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c
> index 249e45c04624..7af351eda003 100644
> --- a/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c
> +++ b/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c
> @@ -9,6 +9,8 @@
>  
>  #include <PiPei.h>
>  
> +#include <Library/ArmHvcLib.h>
> +#include <Library/ArmSmcLib.h>
>  #include <Library/MemoryAllocationLib.h>
>  #include <Library/DebugLib.h>
>  #include <Library/HobLib.h>
> @@ -16,15 +18,113 @@
>  #include <Library/PeiServicesLib.h>
>  #include <libfdt.h>
>  
> +#include <IndustryStandard/ArmStdSmc.h>
> +
>  #include <Guid/EarlyPL011BaseAddress.h>
>  #include <Guid/FdtHob.h>
>  
> +#include <Ppi/Reset2.h>
> +
>  STATIC CONST EFI_PEI_PPI_DESCRIPTOR mTpm2DiscoveredPpi = {
>    EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
>    &gOvmfTpmDiscoveredPpiGuid,
>    NULL
>  };
>  
> +/**
> +  The ResetSystem function resets the entire platform.
> +
> +  @param[in] ResetType      The type of reset to perform.
> +  @param[in] ResetStatus    The status code for the reset.
> +  @param[in] DataSize       The size, in bytes, of ResetData.
> +  @param[in] ResetData      For a ResetType of EfiResetCold, EfiResetWarm, or
> +                            EfiResetShutdown the data buffer starts with a
> +                            Null-terminated string, optionally followed by
> +                            additional binary data. The string is a description
> +                            that the caller may use to further indicate the
> +                            reason for the system reset.
> +**/
> +STATIC
> +VOID
> +EFIAPI
> +ResetSystemHvc (
> +  IN EFI_RESET_TYPE               ResetType,
> +  IN EFI_STATUS                   ResetStatus,
> +  IN UINTN                        DataSize,
> +  IN VOID                         *ResetData OPTIONAL
> +  )
> +{
> +  ARM_HVC_ARGS  ArmHvcArgs;
> +
> +  switch (ResetType) {
> +  case EfiResetWarm:
> +  case EfiResetCold:
> +  case EfiResetPlatformSpecific:
> +    // Send a PSCI 0.2 SYSTEM_RESET command
> +    ArmHvcArgs.Arg0 = ARM_SMC_ID_PSCI_SYSTEM_RESET;
> +    break;
> +
> +  case EfiResetShutdown:
> +    // Send a PSCI 0.2 SYSTEM_OFF command
> +    ArmHvcArgs.Arg0 = ARM_SMC_ID_PSCI_SYSTEM_OFF;
> +    break;
> +
> +  default:
> +    ASSERT (FALSE);
> +    return;
> +  }
> +  ArmCallHvc (&ArmHvcArgs);
> +}
> +
> +STATIC
> +VOID
> +EFIAPI
> +ResetSystemSmc (
> +  IN EFI_RESET_TYPE               ResetType,
> +  IN EFI_STATUS                   ResetStatus,
> +  IN UINTN                        DataSize,
> +  IN VOID                         *ResetData OPTIONAL
> +  )
> +{
> +  ARM_SMC_ARGS  ArmSmcArgs;
> +
> +  switch (ResetType) {
> +  case EfiResetWarm:
> +  case EfiResetCold:
> +  case EfiResetPlatformSpecific:
> +    // Send a PSCI 0.2 SYSTEM_RESET command
> +    ArmSmcArgs.Arg0 = ARM_SMC_ID_PSCI_SYSTEM_RESET;
> +    break;
> +
> +  case EfiResetShutdown:
> +    // Send a PSCI 0.2 SYSTEM_OFF command
> +    ArmSmcArgs.Arg0 = ARM_SMC_ID_PSCI_SYSTEM_OFF;
> +    break;
> +
> +  default:
> +    ASSERT (FALSE);
> +    return;
> +  }
> +  ArmCallSmc (&ArmSmcArgs);
> +}
> +
> +STATIC CONST EFI_PEI_RESET2_PPI mPpiReset[] = {
> +  { ResetSystemHvc },
> +  { ResetSystemSmc },
> +};
> +
> +STATIC CONST EFI_PEI_PPI_DESCRIPTOR mPlatformHvcResetPpi = {
> +  EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
> +  &gEfiPeiReset2PpiGuid,
> +  (EFI_PEI_RESET2_PPI *)&mPpiReset[0]
> +};
> +
> +STATIC CONST EFI_PEI_PPI_DESCRIPTOR mPlatformSmcResetPpi = {
> +  EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
> +  &gEfiPeiReset2PpiGuid,
> +  (EFI_PEI_RESET2_PPI *)&mPpiReset[1]
> +};
> +
>  EFI_STATUS
>  EFIAPI
>  PlatformPeim (
> @@ -47,6 +147,7 @@ PlatformPeim (
>    INT32              StatusLen;
>    CONST UINT64       *RegProp;
>    CONST UINT32       *RangesProp;
> +  CONST VOID         *MethodProp;
>    UINT64             UartBase;
>    UINT64             TpmBase;
>    EFI_STATUS         Status;
> @@ -155,6 +256,28 @@ PlatformPeim (
>          Status = PeiServicesInstallPpi (&mTpm2DiscoveredPpi);
>          ASSERT_EFI_ERROR (Status);
>          break;
> +      } else if (AsciiStrCmp (CompItem, "arm,psci-0.2") == 0) {
> +        MethodProp = fdt_getprop (Base, Node, "method", &Len);
> +        if (MethodProp == NULL) {
> +          DEBUG ((DEBUG_ERROR, "%a: Missing PSCI method property\n",
> +            __FUNCTION__));
> +          break;
> +        }
> +
> +        if (AsciiStrnCmp (MethodProp, "hvc", 3) == 0) {
> +          Status = PeiServicesInstallPpi (&mPlatformHvcResetPpi);
> +          ASSERT_EFI_ERROR (Status);
> +        } else if (AsciiStrnCmp (MethodProp, "smc", 3) == 0) {
> +          Status = PeiServicesInstallPpi (&mPlatformSmcResetPpi);
> +          ASSERT_EFI_ERROR (Status);
> +        } else {
> +          DEBUG ((DEBUG_ERROR, "%a: Unknown PSCI method \"%a\"\n", __FUNCTION__,
> +            MethodProp));
> +          break;
> +        }
> +        DEBUG ((DEBUG_INFO, "%a: Detected PSCI method \"%a\"\n", __FUNCTION__,
> +          MethodProp));
> +        break;
>        }
>      }
>    }
>