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arm64: head.S: Initialise MPAM EL2 registers and disable traps

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Add code to head.S's el2_setup to detect MPAM and disable any EL2 traps.
This register resets to an unknown value, setting it to the default
parititons/pmg before we enable the MMU is the best thing to do.

Kexec/kdump will depend on this if the previous kernel left the CPU
configured with a restrictive configuration.

If linux is booted at the highest implemented exception level el2_setup
will clear the enable bit, disabling MPAM.

This code can't be enabled until a subsequent patch adds the Kconfig
and cpufeature boiler plate.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241030160317.2528209-3-joey.gouly@arm.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
James Morse 2024-10-30 16:03:12 +00:00 committed by Oliver Upton
parent 83732ce6a0
commit 23b33d1e16
1 changed files with 14 additions and 0 deletions
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14
arch/arm64/include/asm/el2_setup.h
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@ -220,6 +220,19 @@
msr spsr_el2, x0
.endm
.macro __init_el2_mpam
/* Memory Partitioning And Monitoring: disable EL2 traps */
mrs x1, id_aa64pfr0_el1
ubfx x0, x1, #ID_AA64PFR0_EL1_MPAM_SHIFT, #4
cbz x0, .Lskip_mpam_\@ // skip if no MPAM
msr_s SYS_MPAM2_EL2, xzr // use the default partition
// and disable lower traps
mrs_s x0, SYS_MPAMIDR_EL1
tbz x0, #MPAMIDR_EL1_HAS_HCR_SHIFT, .Lskip_mpam_\@ // skip if no MPAMHCR reg
msr_s SYS_MPAMHCR_EL2, xzr // clear TRAP_MPAMIDR_EL1 -> EL2
.Lskip_mpam_\@:
.endm
/**
* Initialize EL2 registers to sane values. This should be called early on all
* cores that were booted in EL2. Note that everything gets initialised as
@ -237,6 +250,7 @@
__init_el2_stage2
__init_el2_gicv3
__init_el2_hstr
__init_el2_mpam
__init_el2_nvhe_idregs
__init_el2_cptr
__init_el2_fgt