[Xen-devel] [PATCH MM-PART3 v3 1/9] xen/arm: Rework HSCTLR_BASE

[Julien Grall <julien.grall@arm.com>]

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 initial value for
SCTLR_EL2/HSCTLR.

Note the defines *_CLEAR are only used to check 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@arm.com>
Reviewed-by: Andrii Anisov <andrii.anisov@epam.com>

---
    Note this patch was part of MM-PART2 before. As this was the only
    patch of the series not merged, it is now part of MM-PART3.

    Changes in v3:
        - Add comment on top of HSCTLR_CLEAR/SCTLR_CLEAR to explain that
        it is only used one time at pre-processing time
        - Fix typo in the commit message
        - Add Andrii's reviewed-by

    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 | 56 ++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 57 insertions(+), 21 deletions(-)

diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index 5f817d473e..18ded49a04 100644
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -224,17 +224,7 @@ 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 ddd3a33108..08094a273e 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -352,15 +352,7 @@ 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..e9d2ae2715 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 +138,58 @@
 #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)
+
+/* Only used a pre-processing time... */
+#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)
+
+/* Only used a pre-processing time... */
+#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 */
-- 
2.11.0


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