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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH MM-PART2 RESEND v2 04/19] xen/arm: Rework HSCTLR_BASE
On Tue, 14 May 2019, Julien Grall wrote:
> The current value of HSCTLR_BASE for Arm64 is pretty wrong. It would
> actually turn on SCTLR_EL2.nAA (bit 6) on hardware implementing
> ARMv8.4-LSE.
>
> Furthermore, the documentation of what is cleared/set in SCTLR_EL2 is
> also not correct and looks like to be a verbatim copy from Arm32.
>
> HSCTLR_BASE is replaced with a bunch of per-architecture new defines
> helping to understand better what is the initialie value for
> SCTLR_EL2/HSCTLR.
>
> Note the defines *_CLEAR are only used to check the state of each bits
> are known.
So basically the only purpose of HSCTLR_CLEAR is to execute:
#if (HSCTLR_SET ^ HSCTLR_CLEAR) != 0xffffffffU
Right? It is good to have the check.
Please add a one-line comment on top of HSCTLR_CLEAR -- "only used to
check that the state of each bits are known".
> Lastly, the documentation is dropped from arm{32,64}/head.S as it would
> be pretty easy to get out-of-sync with the definitions.
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
>
> ---
> Changes in v2:
> - Use BIT(..., UL) instead of _BITUL
> ---
> xen/arch/arm/arm32/head.S | 12 +--------
> xen/arch/arm/arm64/head.S | 10 +-------
> xen/include/asm-arm/processor.h | 54
> ++++++++++++++++++++++++++++++++++++++++-
> 3 files changed, 55 insertions(+), 21 deletions(-)
>
> diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
> index 454d24537c..8a98607459 100644
> --- a/xen/arch/arm/arm32/head.S
> +++ b/xen/arch/arm/arm32/head.S
> @@ -234,17 +234,7 @@ cpu_init_done:
> ldr r0,
> =(TCR_RES1|TCR_SH0_IS|TCR_ORGN0_WBWA|TCR_IRGN0_WBWA|TCR_T0SZ(0))
> mcr CP32(r0, HTCR)
>
> - /*
> - * Set up the HSCTLR:
> - * Exceptions in LE ARM,
> - * Low-latency IRQs disabled,
> - * Write-implies-XN disabled (for now),
> - * D-cache disabled (for now),
> - * I-cache enabled,
> - * Alignment checking enabled,
> - * MMU translation disabled (for now).
> - */
> - ldr r0, =(HSCTLR_BASE|SCTLR_Axx_ELx_A)
> + ldr r0, =HSCTLR_SET
> mcr CP32(r0, HSCTLR)
>
> /*
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index 8a6be3352e..4fe904c51d 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -363,15 +363,7 @@ skip_bss:
>
> msr tcr_el2, x0
>
> - /* Set up the SCTLR_EL2:
> - * Exceptions in LE ARM,
> - * Low-latency IRQs disabled,
> - * Write-implies-XN disabled (for now),
> - * D-cache disabled (for now),
> - * I-cache enabled,
> - * Alignment checking disabled,
> - * MMU translation disabled (for now). */
> - ldr x0, =(HSCTLR_BASE)
> + ldr x0, =SCTLR_EL2_SET
> msr SCTLR_EL2, x0
>
> /* Ensure that any exceptions encountered at EL2
> diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
> index bbcba061ca..9afc3786c5 100644
> --- a/xen/include/asm-arm/processor.h
> +++ b/xen/include/asm-arm/processor.h
> @@ -127,6 +127,9 @@
> #define SCTLR_A32_ELx_TE BIT(30, UL)
> #define SCTLR_A32_ELx_FI BIT(21, UL)
>
> +/* Common bits for SCTLR_ELx for Arm64 */
> +#define SCTLR_A64_ELx_SA BIT(3, UL)
> +
> /* Common bits for SCTLR_ELx on all architectures */
> #define SCTLR_Axx_ELx_EE BIT(25, UL)
> #define SCTLR_Axx_ELx_WXN BIT(19, UL)
> @@ -135,7 +138,56 @@
> #define SCTLR_Axx_ELx_A BIT(1, UL)
> #define SCTLR_Axx_ELx_M BIT(0, UL)
>
> -#define HSCTLR_BASE _AC(0x30c51878,U)
> +#ifdef CONFIG_ARM_32
> +
> +#define HSCTLR_RES1 (BIT( 3, UL) | BIT( 4, UL) | BIT( 5, UL) |\
> + BIT( 6, UL) | BIT(11, UL) | BIT(16, UL) |\
> + BIT(18, UL) | BIT(22, UL) | BIT(23, UL) |\
> + BIT(28, UL) | BIT(29, UL))
> +
> +#define HSCTLR_RES0 (BIT(7, UL) | BIT(8, UL) | BIT(9, UL) | BIT(10,
> UL) |\
> + BIT(13, UL) | BIT(14, UL) | BIT(15, UL) | BIT(17,
> UL) |\
> + BIT(20, UL) | BIT(24, UL) | BIT(26, UL) | BIT(27,
> UL) |\
> + BIT(31, UL))
> +
> +/* Initial value for HSCTLR */
> +#define HSCTLR_SET (HSCTLR_RES1 | SCTLR_Axx_ELx_A |
> SCTLR_Axx_ELx_I)
As far as my calculations go, it looks like the only difference is
SCTLR_Axx_ELx_A compared to 0x30c51878, right? Which is the alignment
check.
> +#define HSCTLR_CLEAR (HSCTLR_RES0 | SCTLR_Axx_ELx_M |\
> + SCTLR_Axx_ELx_C | SCTLR_Axx_ELx_WXN |\
> + SCTLR_A32_ELx_FI | SCTLR_Axx_ELx_EE |\
> + SCTLR_A32_ELx_TE)
> +
> +#if (HSCTLR_SET ^ HSCTLR_CLEAR) != 0xffffffffU
> +#error "Inconsistent HSCTLR set/clear bits"
> +#endif
> +
> +#else
> +
> +#define SCTLR_EL2_RES1 (BIT( 4, UL) | BIT( 5, UL) | BIT(11, UL) |\
> + BIT(16, UL) | BIT(18, UL) | BIT(22, UL) |\
> + BIT(23, UL) | BIT(28, UL) | BIT(29, UL))
> +
> +#define SCTLR_EL2_RES0 (BIT( 6, UL) | BIT( 7, UL) | BIT( 8, UL) |\
> + BIT( 9, UL) | BIT(10, UL) | BIT(13, UL) |\
> + BIT(14, UL) | BIT(15, UL) | BIT(17, UL) |\
> + BIT(20, UL) | BIT(21, UL) | BIT(24, UL) |\
> + BIT(26, UL) | BIT(27, UL) | BIT(30, UL) |\
> + BIT(31, UL) | (0xffffffffULL << 32))
> +
> +/* Initial value for SCTLR_EL2 */
> +#define SCTLR_EL2_SET (SCTLR_EL2_RES1 | SCTLR_A64_ELx_SA |\
> + SCTLR_Axx_ELx_I)
Same here, you removed the reserved bits, and added the alignment check,
same as for aarch32. If I got it right, it would be nice to add a
statement like this to the commit message.
> +#define SCTLR_EL2_CLEAR (SCTLR_EL2_RES0 | SCTLR_Axx_ELx_M |\
> + SCTLR_Axx_ELx_A | SCTLR_Axx_ELx_C |\
> + SCTLR_Axx_ELx_WXN | SCTLR_Axx_ELx_EE)
> +
> +#if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffffffffffffUL
> +#error "Inconsistent SCTLR_EL2 set/clear bits"
> +#endif
> +
> +#endif
>
> /* HCR Hyp Configuration Register */
> #define HCR_RW (_AC(1,UL)<<31) /* Register Width, ARM64 only */
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