Commit 23b33d1e authored by James Morse's avatar James Morse Committed by Oliver Upton
Browse files

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



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: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarJoey Gouly <joey.gouly@arm.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Tested-by: default avatarShameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241030160317.2528209-3-joey.gouly@arm.com


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 83732ce6

arch/arm64/include/asm/el2_setup.h

+14 −0
Original line number Diff line number Diff line
@@ -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