[PATCH 5/6] arm64: Add the arm64.nosme command line option
Marc Zyngier
maz at kernel.org
Mon Jun 27 08:14:11 PDT 2022
In order to be able to completely disable SME even if the HW
seems to support it (most likely because the FW is broken),
move the SME setup into the EL2 finalisation block, and
use a new idreg override to deal with it.
Note that we also nuke id_aa64smfr0_el1 as a byproduct.
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
.../admin-guide/kernel-parameters.txt | 3 ++
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/include/asm/el2_setup.h | 45 -------------------
arch/arm64/kernel/cpufeature.c | 4 +-
arch/arm64/kernel/hyp-stub.S | 41 +++++++++++++++++
arch/arm64/kernel/idreg-override.c | 19 +++++++-
6 files changed, 66 insertions(+), 47 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2522b11e593f..301d2d0fee80 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -400,6 +400,9 @@
arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
support
+ arm64.nosme [ARM64] Unconditionally disable Scalable Matrix
+ Extension support
+
ataflop= [HW,M68k]
atarimouse= [HW,MOUSE] Atari Mouse
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 14a8f3d93add..5adda12b1946 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -909,6 +909,7 @@ static inline unsigned int get_vmid_bits(u64 mmfr1)
extern struct arm64_ftr_override id_aa64mmfr1_override;
extern struct arm64_ftr_override id_aa64pfr1_override;
+extern struct arm64_ftr_override id_aa64smfr0_override;
extern struct arm64_ftr_override id_aa64isar1_override;
extern struct arm64_ftr_override id_aa64isar2_override;
diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index 34ceff08cac4..18641dce5184 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -143,50 +143,6 @@
.Lskip_sve_\@:
.endm
-/* SME register access and priority mapping */
-.macro __init_el2_nvhe_sme
- mrs x1, id_aa64pfr1_el1
- ubfx x1, x1, #ID_AA64PFR1_SME_SHIFT, #4
- cbz x1, .Lskip_sme_\@
-
- bic x0, x0, #CPTR_EL2_TSM // Also disable SME traps
- msr cptr_el2, x0 // Disable copro. traps to EL2
- isb
-
- mrs x1, sctlr_el2
- orr x1, x1, #SCTLR_ELx_ENTP2 // Disable TPIDR2 traps
- msr sctlr_el2, x1
- isb
-
- mov x1, #0 // SMCR controls
-
- mrs_s x2, SYS_ID_AA64SMFR0_EL1
- ubfx x2, x2, #ID_AA64SMFR0_FA64_SHIFT, #1 // Full FP in SM?
- cbz x2, .Lskip_sme_fa64_\@
-
- orr x1, x1, SMCR_ELx_FA64_MASK
-.Lskip_sme_fa64_\@:
-
- orr x1, x1, #SMCR_ELx_LEN_MASK // Enable full SME vector
- msr_s SYS_SMCR_EL2, x1 // length for EL1.
-
- mrs_s x1, SYS_SMIDR_EL1 // Priority mapping supported?
- ubfx x1, x1, #SMIDR_EL1_SMPS_SHIFT, #1
- cbz x1, .Lskip_sme_\@
-
- msr_s SYS_SMPRIMAP_EL2, xzr // Make all priorities equal
-
- mrs x1, id_aa64mmfr1_el1 // HCRX_EL2 present?
- ubfx x1, x1, #ID_AA64MMFR1_HCX_SHIFT, #4
- cbz x1, .Lskip_sme_\@
-
- mrs_s x1, SYS_HCRX_EL2
- orr x1, x1, #HCRX_EL2_SMPME_MASK // Enable priority mapping
- msr_s SYS_HCRX_EL2, x1
-
-.Lskip_sme_\@:
-.endm
-
/* Disable any fine grained traps */
.macro __init_el2_fgt
mrs x1, id_aa64mmfr0_el1
@@ -251,7 +207,6 @@
__init_el2_nvhe_idregs
__init_el2_nvhe_cptr
__init_el2_nvhe_sve
- __init_el2_nvhe_sme
__init_el2_fgt
__init_el2_nvhe_prepare_eret
.endm
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 8d88433de81d..9a7b16347a3f 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -632,6 +632,7 @@ static const struct arm64_ftr_bits ftr_raz[] = {
struct arm64_ftr_override __ro_after_init id_aa64mmfr1_override;
struct arm64_ftr_override __ro_after_init id_aa64pfr1_override;
+struct arm64_ftr_override __ro_after_init id_aa64smfr0_override;
struct arm64_ftr_override __ro_after_init id_aa64isar1_override;
struct arm64_ftr_override __ro_after_init id_aa64isar2_override;
@@ -672,7 +673,8 @@ static const struct __ftr_reg_entry {
ARM64_FTR_REG_OVERRIDE(SYS_ID_AA64PFR1_EL1, ftr_id_aa64pfr1,
&id_aa64pfr1_override),
ARM64_FTR_REG(SYS_ID_AA64ZFR0_EL1, ftr_id_aa64zfr0),
- ARM64_FTR_REG(SYS_ID_AA64SMFR0_EL1, ftr_id_aa64smfr0),
+ ARM64_FTR_REG_OVERRIDE(SYS_ID_AA64SMFR0_EL1, ftr_id_aa64smfr0,
+ &id_aa64smfr0_override),
/* Op1 = 0, CRn = 0, CRm = 5 */
ARM64_FTR_REG(SYS_ID_AA64DFR0_EL1, ftr_id_aa64dfr0),
diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 4a02a73650db..1b61ad63f6f5 100644
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -91,6 +91,47 @@ SYM_CODE_START_LOCAL(elx_sync)
SYM_CODE_END(elx_sync)
SYM_CODE_START_LOCAL(__finalise_el2)
+ check_override id_aa64pfr1 ID_AA64PFR1_SME_SHIFT .Linit_sme .Lskip_sme
+
+.Linit_sme: /* SME register access and priority mapping */
+ msr cptr_el2, x0 // Disable SME traps
+ bic x0, x0, #CPTR_EL2_TSM
+ msr cptr_el2, x0
+ isb
+
+ mrs x1, sctlr_el2
+ orr x1, x1, #SCTLR_ELx_ENTP2 // Disable TPIDR2 traps
+ msr sctlr_el2, x1
+ isb
+
+ mov x1, #0 // SMCR controls
+
+ mrs_s x2, SYS_ID_AA64SMFR0_EL1
+ ubfx x2, x2, #ID_AA64SMFR0_FA64_SHIFT, #1 // Full FP in SM?
+ cbz x2, .Lskip_sme_fa64
+
+ orr x1, x1, SMCR_ELx_FA64_MASK
+.Lskip_sme_fa64:
+
+ orr x1, x1, #SMCR_ELx_LEN_MASK // Enable full SME vector
+ msr_s SYS_SMCR_EL2, x1 // length for EL1.
+
+ mrs_s x1, SYS_SMIDR_EL1 // Priority mapping supported?
+ ubfx x1, x1, #SMIDR_EL1_SMPS_SHIFT, #1
+ cbz x1, .Lskip_sme
+
+ msr_s SYS_SMPRIMAP_EL2, xzr // Make all priorities equal
+
+ mrs x1, id_aa64mmfr1_el1 // HCRX_EL2 present?
+ ubfx x1, x1, #ID_AA64MMFR1_HCX_SHIFT, #4
+ cbz x1, .Lskip_sme
+
+ mrs_s x1, SYS_HCRX_EL2
+ orr x1, x1, #HCRX_EL2_SMPME_MASK // Enable priority mapping
+ msr_s SYS_HCRX_EL2, x1
+
+.Lskip_sme:
+
// nVHE? No way! Give me the real thing!
// Sanity check: MMU *must* be off
mrs x1, sctlr_el2
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 6abff337b23b..d018df6cebf1 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -49,12 +49,28 @@ static const struct ftr_set_desc mmfr1 __initconst = {
},
};
+static bool __init pfr1_sme_filter(u64 val)
+{
+ /*
+ * Similarly to SVE, disabling SME also means disabling all
+ * the features that are associated with it. Just set
+ * id_aa64smfr0_el1 to 0 and don't look back.
+ */
+ if (!val) {
+ id_aa64smfr0_override.val = 0;
+ id_aa64smfr0_override.mask = GENMASK(63, 0);
+ }
+
+ return true;
+}
+
static const struct ftr_set_desc pfr1 __initconst = {
.name = "id_aa64pfr1",
.override = &id_aa64pfr1_override,
.fields = {
{ "bt", ID_AA64PFR1_BT_SHIFT },
- { "mte", ID_AA64PFR1_MTE_SHIFT},
+ { "mte", ID_AA64PFR1_MTE_SHIFT },
+ { "sme", ID_AA64PFR1_SME_SHIFT, pfr1_sme_filter },
{}
},
};
@@ -108,6 +124,7 @@ static const struct {
} aliases[] __initconst = {
{ "kvm-arm.mode=nvhe", "id_aa64mmfr1.vh=0" },
{ "kvm-arm.mode=protected", "id_aa64mmfr1.vh=0" },
+ { "arm64.nosme", "id_aa64pfr1.sme=0" },
{ "arm64.nobti", "id_aa64pfr1.bt=0" },
{ "arm64.nopauth",
"id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
--
2.34.1
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