[PATCH 0/2] docs: arm64: Document MDCR_EL3 boot requirements

[PATCH 0/2] docs: arm64: Document MDCR_EL3 boot requirements

[Anshuman Khandual]

This series adds missing MDCR_EL3 boot requirements for debug and pmu
registers that are currently being accessed in the kernel. Please refer
the following link for some earlier discussions on this.

https://lore.kernel.org/all/ZxfOeqyb3RvsdYbU@J2N7QTR9R3/

This series applies on v6.13-rc1

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Anshuman Khandual (2):
  docs: arm64: Document EL3 requirements for cpu debug architecture
  docs: arm64: Document EL3 requirements for FEAT_PMUv3

 Documentation/arch/arm64/booting.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

-- 
2.30.2

[PATCH 1/2] docs: arm64: Document EL3 requirements for cpu debug architecture

[Anshuman Khandual]

This documents EL3 requirements for debug architecture. The register field
MDCR_EL3.TDA needs to be cleared for accesses into debug registers without
any trap being generated into EL3. CPU debug registers like DBGBCR<n>_EL1,
DBGBVR<n>_EL1, DBGWCR<n>_EL1, DBGWVR<n>_EL1 and MDSCR_EL1 are already being
accessed for HW breakpoint, watchpoint and debug monitor implementations on
the platform.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 Documentation/arch/arm64/booting.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/arch/arm64/booting.rst b/Documentation/arch/arm64/booting.rst
index 3278fb4bf219..1b3ac1394e5f 100644
--- a/Documentation/arch/arm64/booting.rst
+++ b/Documentation/arch/arm64/booting.rst
@@ -449,6 +449,12 @@ Before jumping into the kernel, the following conditions must be met:
 
     - HFGWTR_EL2.nGCS_EL0 (bit 52) must be initialised to 0b1.
 
+ - For CPUs with debug architecture i.e FEAT_Debugv8pN (all versions):
+
+ - If EL3 is present:
+
+   - MDCR_EL3.TDA (bit 9) must be initialized to 0b0
+
 The requirements described above for CPU mode, caches, MMUs, architected
 timers, coherency and system registers apply to all CPUs.  All CPUs must
 enter the kernel in the same exception level.  Where the values documented
-- 
2.30.2

[PATCH 2/2] docs: arm64: Document EL3 requirements for FEAT_PMUv3

[Anshuman Khandual]

This documents EL3 requirements for FEAT_PMUv3. The register field MDCR_EL3
.TPM needs to be cleared for accesses into PMU registers without any trap
being generated into EL3. PMUv3 registers like PMCCFILTR_EL0, PMCCNTR_EL0
PMCNTENCLR_EL0, PMCNTENSET_EL0, PMCR_EL0, PMEVCNTR<n>_EL0, PMEVTYPER<n>_EL0
etc are already being accessed for perf HW PMU implementation.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 Documentation/arch/arm64/booting.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/arch/arm64/booting.rst b/Documentation/arch/arm64/booting.rst
index 1b3ac1394e5f..60b16f00d0a8 100644
--- a/Documentation/arch/arm64/booting.rst
+++ b/Documentation/arch/arm64/booting.rst
@@ -455,6 +455,12 @@ Before jumping into the kernel, the following conditions must be met:
 
    - MDCR_EL3.TDA (bit 9) must be initialized to 0b0
 
+ - For CPUs with FEAT_PMUv3:
+
+ - If EL3 is present:
+
+   - MDCR_EL3.TPM (bit 6) must be initialized to 0b0
+
 The requirements described above for CPU mode, caches, MMUs, architected
 timers, coherency and system registers apply to all CPUs.  All CPUs must
 enter the kernel in the same exception level.  Where the values documented
-- 
2.30.2

Re: [PATCH 0/2] docs: arm64: Document MDCR_EL3 boot requirements

[Anshuman Khandual]

On 12/11/24 12:24, Anshuman Khandual wrote:
> This series adds missing MDCR_EL3 boot requirements for debug and pmu
> registers that are currently being accessed in the kernel. Please refer
> the following link for some earlier discussions on this.
> 
> https://lore.kernel.org/all/ZxfOeqyb3RvsdYbU@J2N7QTR9R3/
> 
> This series applies on v6.13-rc1
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-doc@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> 
> Anshuman Khandual (2):
>   docs: arm64: Document EL3 requirements for cpu debug architecture
>   docs: arm64: Document EL3 requirements for FEAT_PMUv3
> 
>  Documentation/arch/arm64/booting.rst | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 

Gentle ping, any updates on this.

Re: [PATCH 0/2] docs: arm64: Document MDCR_EL3 boot requirements

[Will Deacon]

On Wed, 11 Dec 2024 12:24:23 +0530, Anshuman Khandual wrote:
> This series adds missing MDCR_EL3 boot requirements for debug and pmu
> registers that are currently being accessed in the kernel. Please refer
> the following link for some earlier discussions on this.
> 
> https://lore.kernel.org/all/ZxfOeqyb3RvsdYbU@J2N7QTR9R3/
> 
> This series applies on v6.13-rc1
> 
> [...]

Applied to arm64 (for-next/docs), thanks!

[1/2] docs: arm64: Document EL3 requirements for cpu debug architecture
      https://git.kernel.org/arm64/c/3e5be4e11aac
[2/2] docs: arm64: Document EL3 requirements for FEAT_PMUv3
      https://git.kernel.org/arm64/c/1e4a5e3679cc

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev