Re: [edk2-devel] [PATCH v6 4/5] MdePkg: Utilize Cache Management Operations Implementation For RISC-V

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

On 10/21/23 19:33, Dhaval Sharma wrote:
> Use newly defined cache management operations for RISC-V where possible
> It builds up on the support added for RISC-V cache management
> instructions in BaseLib.
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> 
> Signed-off-by: Dhaval Sharma <dhaval@rivosinc.com>
> ---
> 
> Notes:
>     V1:
>     - Utilize cache management instructions if HW supports it
>       This patch is part of restructuring on top of v5
> 
>  MdePkg/MdePkg.dec                                                  |   8 +
>  MdePkg/Library/BaseCacheMaintenanceLib/BaseCacheMaintenanceLib.inf |   2 +
>  MdePkg/Library/BaseCacheMaintenanceLib/RiscVCache.c                | 159 +++++++++++++++++---
>  MdePkg/MdePkg.uni                                                  |   4 +
>  4 files changed, 154 insertions(+), 19 deletions(-)
> 
> diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec
> index ac54338089e8..fa92673ff633 100644
> --- a/MdePkg/MdePkg.dec
> +++ b/MdePkg/MdePkg.dec
> @@ -2399,6 +2399,14 @@ [PcdsFixedAtBuild.AARCH64, PcdsPatchableInModule.AARCH64]
>    # @Prompt CPU Rng algorithm's GUID.
>    gEfiMdePkgTokenSpaceGuid.PcdCpuRngSupportedAlgorithm|{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}|VOID*|0x00000037
>  
> +[PcdsFixedAtBuild.RISCV64, PcdsPatchableInModule.RISCV64]
> +  #
> +  # Configurability to override RISC-V CPU Features
> +  # BIT 0 = Cache Management Operations. This bit is relevant only if
> +  # previous stage has feature enabled and user wants to disable it.
> +  #
> +  gEfiMdePkgTokenSpaceGuid.PcdRiscVFeatureOverride|0xFFFFFFFFFFFFFFFF|UINT64|0x69
> +
>  [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
>    ## This value is used to set the base address of PCI express hierarchy.
>    # @Prompt PCI Express Base Address.
> diff --git a/MdePkg/Library/BaseCacheMaintenanceLib/BaseCacheMaintenanceLib.inf b/MdePkg/Library/BaseCacheMaintenanceLib/BaseCacheMaintenanceLib.inf
> index 6fd9cbe5f6c9..39a7fb963b49 100644
> --- a/MdePkg/Library/BaseCacheMaintenanceLib/BaseCacheMaintenanceLib.inf
> +++ b/MdePkg/Library/BaseCacheMaintenanceLib/BaseCacheMaintenanceLib.inf
> @@ -56,3 +56,5 @@ [LibraryClasses]
>    BaseLib
>    DebugLib
>  
> +[Pcd.RISCV64]
> +  gEfiMdePkgTokenSpaceGuid.PcdRiscVFeatureOverride  ## CONSUMES
> diff --git a/MdePkg/Library/BaseCacheMaintenanceLib/RiscVCache.c b/MdePkg/Library/BaseCacheMaintenanceLib/RiscVCache.c
> index 4eb18edb9aa7..6851970c9e16 100644
> --- a/MdePkg/Library/BaseCacheMaintenanceLib/RiscVCache.c
> +++ b/MdePkg/Library/BaseCacheMaintenanceLib/RiscVCache.c
> @@ -1,7 +1,8 @@
>  /** @file
> -  RISC-V specific functionality for cache.
> +  Implement Risc-V Cache Management Operations
>  
>    Copyright (c) 2020, Hewlett Packard Enterprise Development LP. All rights reserved.<BR>
> +  Copyright (c) 2023, Rivos Inc. All rights reserved.<BR>
>  
>    SPDX-License-Identifier: BSD-2-Clause-Patent
>  **/
> @@ -9,10 +10,111 @@
>  #include <Base.h>
>  #include <Library/BaseLib.h>
>  #include <Library/DebugLib.h>
> +#include <Library/PcdLib.h>

One nit: given that we're introducing a PcdLib dependency here, we
should also add the following to the library instance INF file:

[LibraryClasses.RISCV64]
  PcdLib

I've not deeply verified the implementation in this patch, but
structurally it looks OK to me. So you can add:

Acked-by: Laszlo Ersek <lersek@redhat.com>

to the next version (with the LibraryClasses addition).

Thanks
Laszlo


> +
> +// TODO: This will be removed once RISC-V CPU HOB is available
> +#define RISCV_CACHE_BLOCK_SIZE         64
> +#define RISCV_CPU_FEATURE_CMO_BITMASK  0x1
> +
> +typedef enum {
> +  Clean,
> +  Flush,
> +  Invld,
> +} CACHE_OP;
> +
> +/**
> +Verify CBOs are supported by this HW
> +TODO: Use RISC-V CPU HOB once available.
> +
> +**/
> +STATIC
> +BOOLEAN
> +RiscVIsCMOEnabled (
> +  VOID
> +  )
> +{
> +  // TODO: Add check for CMO from CPU HOB.
> +  // If CMO is disabled in HW, skip Override check
> +  // Otherwise this PCD can override settings
> +  return ((PcdGet64 (PcdRiscVFeatureOverride) & RISCV_CPU_FEATURE_CMO_BITMASK) != 0);
> +}
> +
> +/**
> +  Performs required opeartion on cache lines in the cache coherency domain
> +  of the calling CPU. If Address is not aligned on a cache line boundary,
> +  then entire cache line containing Address is operated. If Address + Length
> +  is not aligned on a cache line boundary, then the entire cache line
> +  containing Address + Length -1 is operated.
> +  If Length is greater than (MAX_ADDRESS - Address + 1), then ASSERT().
> +  @param  Address The base address of the cache lines to
> +          invalidate.
> +  @param  Length  The number of bytes to invalidate from the instruction
> +          cache.
> +  @param  Op  Type of CMO operation to be performed
> +  @return Address.
> +
> +**/
> +STATIC
> +VOID
> +CacheOpCacheRange (
> +  IN VOID      *Address,
> +  IN UINTN     Length,
> +  IN CACHE_OP  Op
> +  )
> +{
> +  UINTN  CacheLineSize;
> +  UINTN  Start;
> +  UINTN  End;
> +
> +  if (Length == 0) {
> +    return;
> +  }
> +
> +  if ((Op != Invld) && (Op != Flush) && (Op != Clean)) {
> +    return;
> +  }
> +
> +  ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)Address));
> +
> +  CacheLineSize = RISCV_CACHE_BLOCK_SIZE;
> +
> +  Start = (UINTN)Address;
> +  //
> +  // Calculate the cache line alignment
> +  //
> +  End    = (Start + Length + (CacheLineSize - 1)) & ~(CacheLineSize - 1);
> +  Start &= ~((UINTN)CacheLineSize - 1);
> +
> +  DEBUG (
> +    (DEBUG_INFO,
> +     "%a Performing Cache Management Operation %d \n", __func__, Op)
> +    );
> +
> +  do {
> +    switch (Op) {
> +      case Invld:
> +        RiscVCpuCacheInvalAsmCbo (Start);
> +        break;
> +      case Flush:
> +        RiscVCpuCacheFlushAsmCbo (Start);
> +        break;
> +      case Clean:
> +        RiscVCpuCacheCleanAsmCbo (Start);
> +        break;
> +      default:
> +        break;
> +    }
> +
> +    Start = Start + CacheLineSize;
> +  } while (Start != End);
> +}
>  
>  /**
>    Invalidates the entire instruction cache in cache coherency domain of the
> -  calling CPU.
> +  calling CPU. Risc-V does not have currently an CBO implementation which can
> +  invalidate entire I-cache. Hence using Fence instruction for now. P.S. Fence
> +  instruction may or may not implement full I-cache invd functionality on all
> +  implementations.
>  
>  **/
>  VOID
> @@ -56,12 +158,17 @@ InvalidateInstructionCacheRange (
>    IN UINTN  Length
>    )
>  {
> -  DEBUG (
> -    (DEBUG_WARN,
> -     "%a:RISC-V unsupported function.\n"
> -     "Invalidating the whole instruction cache instead.\n", __func__)
> -    );
> -  InvalidateInstructionCache ();
> +  if (RiscVIsCMOEnabled ()) {
> +    CacheOpCacheRange (Address, Length, Invld);
> +  } else {
> +    DEBUG (
> +      (DEBUG_WARN,
> +       "%a:RISC-V unsupported function.\n"
> +       "Invalidating the whole instruction cache instead.\n", __func__)
> +      );
> +    InvalidateInstructionCache ();
> +  }
> +
>    return Address;
>  }
>  
> @@ -117,7 +224,12 @@ WriteBackInvalidateDataCacheRange (
>    IN      UINTN  Length
>    )
>  {
> -  DEBUG ((DEBUG_ERROR, "%a:RISC-V unsupported function.\n", __func__));
> +  if (RiscVIsCMOEnabled ()) {
> +    CacheOpCacheRange (Address, Length, Flush);
> +  } else {
> +    DEBUG ((DEBUG_ERROR, "%a:RISC-V unsupported function.\n", __func__));
> +  }
> +
>    return Address;
>  }
>  
> @@ -156,10 +268,7 @@ WriteBackDataCache (
>  
>    If Length is greater than (MAX_ADDRESS - Address + 1), then ASSERT().
>  
> -  @param  Address The base address of the data cache lines to write back. If
> -                  the CPU is in a physical addressing mode, then Address is a
> -                  physical address. If the CPU is in a virtual addressing
> -                  mode, then Address is a virtual address.
> +  @param  Address The base address of the data cache lines to write back.
>    @param  Length  The number of bytes to write back from the data cache.
>  
>    @return Address of cache written in main memory.
> @@ -172,7 +281,12 @@ WriteBackDataCacheRange (
>    IN      UINTN  Length
>    )
>  {
> -  DEBUG ((DEBUG_ERROR, "%a:RISC-V unsupported function.\n", __func__));
> +  if (RiscVIsCMOEnabled ()) {
> +    CacheOpCacheRange (Address, Length, Clean);
> +  } else {
> +    DEBUG ((DEBUG_ERROR, "%a:RISC-V unsupported function.\n", __func__));
> +  }
> +
>    return Address;
>  }
>  
> @@ -214,10 +328,7 @@ InvalidateDataCache (
>  
>    If Length is greater than (MAX_ADDRESS - Address + 1), then ASSERT().
>  
> -  @param  Address The base address of the data cache lines to invalidate. If
> -                  the CPU is in a physical addressing mode, then Address is a
> -                  physical address. If the CPU is in a virtual addressing mode,
> -                  then Address is a virtual address.
> +  @param  Address The base address of the data cache lines to invalidate.
>    @param  Length  The number of bytes to invalidate from the data cache.
>  
>    @return Address.
> @@ -230,6 +341,16 @@ InvalidateDataCacheRange (
>    IN      UINTN  Length
>    )
>  {
> -  DEBUG ((DEBUG_ERROR, "%a:RISC-V unsupported function.\n", __func__));
> +  if (RiscVIsCMOEnabled ()) {
> +    CacheOpCacheRange (Address, Length, Invld);
> +  } else {
> +    DEBUG (
> +      (DEBUG_WARN,
> +       "%a:RISC-V unsupported function.\n"
> +       "Invalidating the whole Data cache instead.\n", __func__)
> +      );
> +    InvalidateDataCache ();
> +  }
> +
>    return Address;
>  }
> diff --git a/MdePkg/MdePkg.uni b/MdePkg/MdePkg.uni
> index 5c1fa24065c7..f49c33191054 100644
> --- a/MdePkg/MdePkg.uni
> +++ b/MdePkg/MdePkg.uni
> @@ -287,6 +287,10 @@
>  
>  #string STR_gEfiMdePkgTokenSpaceGuid_PcdGuidedExtractHandlerTableAddress_HELP  #language en-US "This value is used to set the available memory address to store Guided Extract Handlers. The required memory space is decided by the value of PcdMaximumGuidedExtractHandler."
>  
> +#string STR_gEfiMdePkgTokenSpaceGuid_PcdRiscVFeatureOverride_PROMPT  #language en-US "RISC-V Feature Override"
> +
> +#string STR_gEfiMdePkgTokenSpaceGuid_PcdRiscVFeatureOverride_HELP  #language en-US "This value is used to Override Any RISC-V specific features supported by this PCD"
> +
>  #string STR_gEfiMdePkgTokenSpaceGuid_PcdPciExpressBaseAddress_PROMPT  #language en-US "PCI Express Base Address"
>  
>  #string STR_gEfiMdePkgTokenSpaceGuid_PcdPciExpressBaseAddress_HELP  #language en-US "This value is used to set the base address of PCI express hierarchy."



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