Re: [kvm-unit-tests PATCH v1 2/2] arm64: Define name for the bits used in SCTLR_EL1_RES1

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Hi Eric,

On 7/20/23 01:46, Eric Auger wrote:
Hi Shaoqin,

On 7/19/23 05:19, Shaoqin Huang wrote:
Currently some fields in SCTLR_EL1 don't define a name and directly used
in the SCTLR_EL1_RES1, that's not good now since these fields have been
functional and have a name.

According to the ARM DDI 0487J.a, define the name related to these
fields.

Suggested-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Signed-off-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
---
  lib/arm64/asm/sysreg.h | 13 +++++++++++--
  1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/arm64/asm/sysreg.h b/lib/arm64/asm/sysreg.h
index c7f529d..9c68698 100644
--- a/lib/arm64/asm/sysreg.h
+++ b/lib/arm64/asm/sysreg.h
@@ -80,17 +80,26 @@ asm(
  #define ICC_GRPEN1_EL1			sys_reg(3, 0, 12, 12, 7)
/* System Control Register (SCTLR_EL1) bits */
+#define SCTLR_EL1_LSMAOE	_BITUL(29)
+#define SCTLR_EL1_NTLSMD	_BITUL(28)
  #define SCTLR_EL1_EE		_BITUL(25)
+#define SCTLR_EL1_SPAN		_BITUL(23)
+#define SCTLR_EL1_EIS		_BITUL(22)
+#define SCTLR_EL1_TSCXT		_BITUL(20)
  #define SCTLR_EL1_WXN		_BITUL(19)
  #define SCTLR_EL1_I		_BITUL(12)
+#define SCTLR_EL1_EOS		_BITUL(11)
+#define SCTLR_EL1_SED		_BITUL(8)
+#define SCTLR_EL1_ITD		_BITUL(7)
  #define SCTLR_EL1_SA0		_BITUL(4)
  #define SCTLR_EL1_SA		_BITUL(3)
  #define SCTLR_EL1_C		_BITUL(2)
  #define SCTLR_EL1_A		_BITUL(1)
  #define SCTLR_EL1_M		_BITUL(0)
-#define SCTLR_EL1_RES1 (_BITUL(7) | _BITUL(8) | _BITUL(11) | _BITUL(20) | \
-			 _BITUL(22) | _BITUL(23) | _BITUL(28) | _BITUL(29))
+#define SCTLR_EL1_RES1	(SCTLR_EL1_ITD | SCTLR_EL1_SED | SCTLR_EL1_EOS | \
+			 SCTLR_EL1_TSCXT | SCTLR_EL1_EIS | SCTLR_EL1_SPAN | \
+			 SCTLR_EL1_NTLSMD | SCTLR_EL1_LSMAOE)
  #define INIT_SCTLR_EL1_MMU_OFF	\
  			SCTLR_EL1_RES1
The change looks good to me (although _BITULL remark still holds).

Independently on this patch the _RES1 terminology looks odd to me. For
example ESO bit is RES1 only if FEAT_ExS is not implemented. Maybe I
misunderstand why it was named that way but to me RES1 means another
thing. If confirmed we could simply drop SCTLR_EL1_RES1 which is not
used elsewhere and directly define INIT_SCTLR_EL1_MMU_OF.

The SCTLR_EL1_RES1 was originally defined by commit 10b65ce ("arm64: Configure SCTLR_EL1 at boot"). It seems at that time the BIT(11), yes the EOS bit is undefined, and must be reserved for 1, but now it has a definition which is EOS. It should have no effect if set EOS bit to 1 since its originally res to 1.

SCTLR_EL1_RES1 can simply be dropped since it has no other user.

Thanks,
Shaoqin


Thanks

Eric


--
Shaoqin




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