[PATCH v4 0/3] OvmfPkg/PlatformPei: prefer etc/e820 for memory detection

[PATCH v4 0/3] OvmfPkg/PlatformPei: prefer etc/e820 for memory detection

[Gerd Hoffmann]

Don't use cmos for memory detection if possible.
qemu provides the etc/e820 firmware config file
as alternative since 2013.

v4:
 - uncrustify & rebase to latest master.

v3:
 - fix CI failure.

v2:
 - fix lowmem detection.
 - pick up review tags.
 - add rfc patch to completely drop cmos support.

Gerd Hoffmann (3):
  OvmfPkg/PlatformPei: ScanOrAdd64BitE820Ram improvements
  OvmfPkg/PlatformPei: prefer etc/e820 for memory detection
  RFC: OvmfPkg/PlatformPei: stop using cmos for memory detection

 OvmfPkg/PlatformPei/MemDetect.c | 88 ++++++++++++---------------------
 1 file changed, 31 insertions(+), 57 deletions(-)

-- 
2.33.1

[PATCH v4 1/3] OvmfPkg/PlatformPei: ScanOrAdd64BitE820Ram improvements

[Gerd Hoffmann]

Add a bool parameter to ScanOrAdd64BitE820Ram to explicitly specify
whenever ScanOrAdd64BitE820Ram should add HOBs for high memory (above
4G) or scan only.

Also add a lowmem parameter so ScanOrAdd64BitE820Ram
can report the memory size below 4G.

This allows a more flexible usage of ScanOrAdd64BitE820Ram,
a followup patch will use it for all memory detection.

No functional change.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
---
 OvmfPkg/PlatformPei/MemDetect.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index 3f59a1ac79f6..912889ab9b75 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -216,6 +216,8 @@ QemuUc32BaseInitialization (
 STATIC
 EFI_STATUS
 ScanOrAdd64BitE820Ram (
+  IN BOOLEAN  AddHighHob,
+  OUT UINT64  *LowMemory OPTIONAL,
   OUT UINT64  *MaxAddress OPTIONAL
   )
 {
@@ -234,6 +236,10 @@ ScanOrAdd64BitE820Ram (
     return EFI_PROTOCOL_ERROR;
   }
 
+  if (LowMemory != NULL) {
+    *LowMemory = 0;
+  }
+
   if (MaxAddress != NULL) {
     *MaxAddress = BASE_4GB;
   }
@@ -249,10 +255,8 @@ ScanOrAdd64BitE820Ram (
       E820Entry.Length,
       E820Entry.Type
       ));
-    if ((E820Entry.Type == EfiAcpiAddressRangeMemory) &&
-        (E820Entry.BaseAddr >= BASE_4GB))
-    {
-      if (MaxAddress == NULL) {
+    if (E820Entry.Type == EfiAcpiAddressRangeMemory) {
+      if (AddHighHob && (E820Entry.BaseAddr >= BASE_4GB)) {
         UINT64  Base;
         UINT64  End;
 
@@ -272,11 +276,13 @@ ScanOrAdd64BitE820Ram (
             End
             ));
         }
-      } else {
+      }
+
+      if (MaxAddress || LowMemory) {
         UINT64  Candidate;
 
         Candidate = E820Entry.BaseAddr + E820Entry.Length;
-        if (Candidate > *MaxAddress) {
+        if (MaxAddress && (Candidate > *MaxAddress)) {
           *MaxAddress = Candidate;
           DEBUG ((
             DEBUG_VERBOSE,
@@ -285,6 +291,16 @@ ScanOrAdd64BitE820Ram (
             *MaxAddress
             ));
         }
+
+        if (LowMemory && (Candidate > *LowMemory) && (Candidate < BASE_4GB)) {
+          *LowMemory = Candidate;
+          DEBUG ((
+            DEBUG_VERBOSE,
+            "%a: LowMemory=0x%Lx\n",
+            __FUNCTION__,
+            *LowMemory
+            ));
+        }
       }
     }
   }
@@ -369,7 +385,7 @@ GetFirstNonAddress (
   // Otherwise, get the flat size of the memory above 4GB from the CMOS (which
   // can only express a size smaller than 1TB), and add it to 4GB.
   //
-  Status = ScanOrAdd64BitE820Ram (&FirstNonAddress);
+  Status = ScanOrAdd64BitE820Ram (FALSE, NULL, &FirstNonAddress);
   if (EFI_ERROR (Status)) {
     FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();
   }
@@ -802,7 +818,7 @@ QemuInitializeRam (
     // entries. Otherwise, create a single memory HOB with the flat >=4GB
     // memory size read from the CMOS.
     //
-    Status = ScanOrAdd64BitE820Ram (NULL);
+    Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
     if (EFI_ERROR (Status) && (UpperMemorySize != 0)) {
       AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
     }
-- 
2.33.1

[PATCH v4 2/3] OvmfPkg/PlatformPei: prefer etc/e820 for memory detection

[Gerd Hoffmann]

Prefer the e820 map provided via qemu firmware config interface
for memory detection.  Use rtc cmos only as fallback, which should
be rarely needed these days as qemu supports etc/e820 since 2013.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
---
 OvmfPkg/PlatformPei/MemDetect.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index 912889ab9b75..e0f2caa9cd3c 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -313,8 +313,15 @@ GetSystemMemorySizeBelow4gb (
   VOID
   )
 {
-  UINT8  Cmos0x34;
-  UINT8  Cmos0x35;
+  EFI_STATUS  Status;
+  UINT64      LowerMemorySize = 0;
+  UINT8       Cmos0x34;
+  UINT8       Cmos0x35;
+
+  Status = ScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
+  if ((Status == EFI_SUCCESS) && (LowerMemorySize > 0)) {
+    return (UINT32)LowerMemorySize;
+  }
 
   //
   // CMOS 0x34/0x35 specifies the system memory above 16 MB.
@@ -769,7 +776,6 @@ QemuInitializeRam (
   // Determine total memory size available
   //
   LowerMemorySize = GetSystemMemorySizeBelow4gb ();
-  UpperMemorySize = GetSystemMemorySizeAbove4gb ();
 
   if (mBootMode == BOOT_ON_S3_RESUME) {
     //
@@ -819,8 +825,11 @@ QemuInitializeRam (
     // memory size read from the CMOS.
     //
     Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
-    if (EFI_ERROR (Status) && (UpperMemorySize != 0)) {
-      AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
+    if (EFI_ERROR (Status)) {
+      UpperMemorySize = GetSystemMemorySizeAbove4gb ();
+      if (UpperMemorySize != 0) {
+        AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
+      }
     }
   }
 
-- 
2.33.1

[PATCH v4 3/3] RFC: OvmfPkg/PlatformPei: stop using cmos for memory detection

[Gerd Hoffmann]

Not needed for qemu 1.7 (released in 2013) and newer.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 OvmfPkg/PlatformPei/MemDetect.c | 59 +++------------------------------
 1 file changed, 4 insertions(+), 55 deletions(-)

diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index e0f2caa9cd3c..21b0b9af26a1 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -37,7 +37,6 @@ Module Name:
 #include <Library/QemuFwCfgSimpleParserLib.h>
 
 #include "Platform.h"
-#include "Cmos.h"
 
 UINT8  mPhysMemAddressWidth;
 
@@ -315,51 +314,11 @@ GetSystemMemorySizeBelow4gb (
 {
   EFI_STATUS  Status;
   UINT64      LowerMemorySize = 0;
-  UINT8       Cmos0x34;
-  UINT8       Cmos0x35;
 
   Status = ScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
-  if ((Status == EFI_SUCCESS) && (LowerMemorySize > 0)) {
-    return (UINT32)LowerMemorySize;
-  }
-
-  //
-  // CMOS 0x34/0x35 specifies the system memory above 16 MB.
-  // * CMOS(0x35) is the high byte
-  // * CMOS(0x34) is the low byte
-  // * The size is specified in 64kb chunks
-  // * Since this is memory above 16MB, the 16MB must be added
-  //   into the calculation to get the total memory size.
-  //
-
-  Cmos0x34 = (UINT8)CmosRead8 (0x34);
-  Cmos0x35 = (UINT8)CmosRead8 (0x35);
-
-  return (UINT32)(((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) + SIZE_16MB);
-}
-
-STATIC
-UINT64
-GetSystemMemorySizeAbove4gb (
-  )
-{
-  UINT32  Size;
-  UINTN   CmosIndex;
-
-  //
-  // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.
-  // * CMOS(0x5d) is the most significant size byte
-  // * CMOS(0x5c) is the middle size byte
-  // * CMOS(0x5b) is the least significant size byte
-  // * The size is specified in 64kb chunks
-  //
-
-  Size = 0;
-  for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {
-    Size = (UINT32)(Size << 8) + (UINT32)CmosRead8 (CmosIndex);
-  }
-
-  return LShiftU64 (Size, 16);
+  ASSERT_EFI_ERROR (Status);
+  ASSERT (LowerMemorySize > 0);
+  return (UINT32)LowerMemorySize;
 }
 
 /**
@@ -389,12 +348,9 @@ GetFirstNonAddress (
   // If QEMU presents an E820 map, then get the highest exclusive >=4GB RAM
   // address from it. This can express an address >= 4GB+1TB.
   //
-  // Otherwise, get the flat size of the memory above 4GB from the CMOS (which
-  // can only express a size smaller than 1TB), and add it to 4GB.
-  //
   Status = ScanOrAdd64BitE820Ram (FALSE, NULL, &FirstNonAddress);
   if (EFI_ERROR (Status)) {
-    FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();
+    FirstNonAddress = BASE_4GB;
   }
 
   //
@@ -766,7 +722,6 @@ QemuInitializeRam (
   )
 {
   UINT64         LowerMemorySize;
-  UINT64         UpperMemorySize;
   MTRR_SETTINGS  MtrrSettings;
   EFI_STATUS     Status;
 
@@ -825,12 +780,6 @@ QemuInitializeRam (
     // memory size read from the CMOS.
     //
     Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
-    if (EFI_ERROR (Status)) {
-      UpperMemorySize = GetSystemMemorySizeAbove4gb ();
-      if (UpperMemorySize != 0) {
-        AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
-      }
-    }
   }
 
   //
-- 
2.33.1

Re: [PATCH v4 3/3] RFC: OvmfPkg/PlatformPei: stop using cmos for memory detection

[Ard Biesheuvel]

On Wed, 8 Dec 2021 at 08:02, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> Not needed for qemu 1.7 (released in 2013) and newer.
>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Good riddance

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  OvmfPkg/PlatformPei/MemDetect.c | 59 +++------------------------------
>  1 file changed, 4 insertions(+), 55 deletions(-)
>
> diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
> index e0f2caa9cd3c..21b0b9af26a1 100644
> --- a/OvmfPkg/PlatformPei/MemDetect.c
> +++ b/OvmfPkg/PlatformPei/MemDetect.c
> @@ -37,7 +37,6 @@ Module Name:
>  #include <Library/QemuFwCfgSimpleParserLib.h>
>
>  #include "Platform.h"
> -#include "Cmos.h"
>
>  UINT8  mPhysMemAddressWidth;
>
> @@ -315,51 +314,11 @@ GetSystemMemorySizeBelow4gb (
>  {
>    EFI_STATUS  Status;
>    UINT64      LowerMemorySize = 0;
> -  UINT8       Cmos0x34;
> -  UINT8       Cmos0x35;
>
>    Status = ScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
> -  if ((Status == EFI_SUCCESS) && (LowerMemorySize > 0)) {
> -    return (UINT32)LowerMemorySize;
> -  }
> -
> -  //
> -  // CMOS 0x34/0x35 specifies the system memory above 16 MB.
> -  // * CMOS(0x35) is the high byte
> -  // * CMOS(0x34) is the low byte
> -  // * The size is specified in 64kb chunks
> -  // * Since this is memory above 16MB, the 16MB must be added
> -  //   into the calculation to get the total memory size.
> -  //
> -
> -  Cmos0x34 = (UINT8)CmosRead8 (0x34);
> -  Cmos0x35 = (UINT8)CmosRead8 (0x35);
> -
> -  return (UINT32)(((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) + SIZE_16MB);
> -}
> -
> -STATIC
> -UINT64
> -GetSystemMemorySizeAbove4gb (
> -  )
> -{
> -  UINT32  Size;
> -  UINTN   CmosIndex;
> -
> -  //
> -  // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.
> -  // * CMOS(0x5d) is the most significant size byte
> -  // * CMOS(0x5c) is the middle size byte
> -  // * CMOS(0x5b) is the least significant size byte
> -  // * The size is specified in 64kb chunks
> -  //
> -
> -  Size = 0;
> -  for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {
> -    Size = (UINT32)(Size << 8) + (UINT32)CmosRead8 (CmosIndex);
> -  }
> -
> -  return LShiftU64 (Size, 16);
> +  ASSERT_EFI_ERROR (Status);
> +  ASSERT (LowerMemorySize > 0);
> +  return (UINT32)LowerMemorySize;
>  }
>
>  /**
> @@ -389,12 +348,9 @@ GetFirstNonAddress (
>    // If QEMU presents an E820 map, then get the highest exclusive >=4GB RAM
>    // address from it. This can express an address >= 4GB+1TB.
>    //
> -  // Otherwise, get the flat size of the memory above 4GB from the CMOS (which
> -  // can only express a size smaller than 1TB), and add it to 4GB.
> -  //
>    Status = ScanOrAdd64BitE820Ram (FALSE, NULL, &FirstNonAddress);
>    if (EFI_ERROR (Status)) {
> -    FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();
> +    FirstNonAddress = BASE_4GB;
>    }
>
>    //
> @@ -766,7 +722,6 @@ QemuInitializeRam (
>    )
>  {
>    UINT64         LowerMemorySize;
> -  UINT64         UpperMemorySize;
>    MTRR_SETTINGS  MtrrSettings;
>    EFI_STATUS     Status;
>
> @@ -825,12 +780,6 @@ QemuInitializeRam (
>      // memory size read from the CMOS.
>      //
>      Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
> -    if (EFI_ERROR (Status)) {
> -      UpperMemorySize = GetSystemMemorySizeAbove4gb ();
> -      if (UpperMemorySize != 0) {
> -        AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
> -      }
> -    }
>    }
>
>    //
> --
> 2.33.1
>

Re: [PATCH v4 0/3] OvmfPkg/PlatformPei: prefer etc/e820 for memory detection

[Ard Biesheuvel]

On Wed, 8 Dec 2021 at 08:02, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> Don't use cmos for memory detection if possible.
> qemu provides the etc/e820 firmware config file
> as alternative since 2013.
>
> v4:
>  - uncrustify & rebase to latest master.
>
> v3:
>  - fix CI failure.
>
> v2:
>  - fix lowmem detection.
>  - pick up review tags.
>  - add rfc patch to completely drop cmos support.
>
> Gerd Hoffmann (3):
>   OvmfPkg/PlatformPei: ScanOrAdd64BitE820Ram improvements
>   OvmfPkg/PlatformPei: prefer etc/e820 for memory detection
>   RFC: OvmfPkg/PlatformPei: stop using cmos for memory detection
>

Merged as #2297

Thanks,

>  OvmfPkg/PlatformPei/MemDetect.c | 88 ++++++++++++---------------------
>  1 file changed, 31 insertions(+), 57 deletions(-)
>
> --
> 2.33.1
>