@@ -458,6 +458,9 @@
arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory
Set instructions support
+ arm64.nompam [ARM64] Unconditionally disable Memory Partitioning And
+ Monitoring support
+
arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
support
@@ -294,19 +294,6 @@
.Lskip_gcs_\@:
.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
@@ -324,7 +311,6 @@
__init_el2_stage2
__init_el2_gicv3
__init_el2_hstr
- __init_el2_mpam
__init_el2_nvhe_idregs
__init_el2_cptr
__init_el2_fgt
@@ -371,6 +357,16 @@
#endif
.macro finalise_el2_state
+ check_override id_aa64pfr0, ID_AA64PFR0_EL1_MPAM_SHIFT, .Linit_mpam_\@, .Lskip_mpam_\@, x1, x2
+
+.Linit_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_\@:
check_override id_aa64pfr0, ID_AA64PFR0_EL1_SVE_SHIFT, .Linit_sve_\@, .Lskip_sve_\@, x1, x2
.Linit_sve_\@: /* SVE register access */
@@ -88,6 +88,7 @@
#include <asm/mte.h>
#include <asm/hypervisor.h>
#include <asm/processor.h>
+#include <asm/ptrace.h>
#include <asm/smp.h>
#include <asm/sysreg.h>
#include <asm/traps.h>
@@ -1191,8 +1192,10 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
cpacr_restore(cpacr);
}
- if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0))
+ if (id_aa64pfr0_mpam(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1))) {
+ info->reg_mpamidr = read_cpuid(MPAMIDR_EL1);
init_cpu_ftr_reg(SYS_MPAMIDR_EL1, info->reg_mpamidr);
+ }
if (id_aa64pfr1_mte(info->reg_id_aa64pfr1))
init_cpu_ftr_reg(SYS_GMID_EL1, info->reg_gmid);
@@ -1443,7 +1446,8 @@ void update_cpu_features(int cpu,
cpacr_restore(cpacr);
}
- if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0)) {
+ if (id_aa64pfr0_mpam(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1))) {
+ info->reg_mpamidr = read_cpuid(MPAMIDR_EL1);
taint |= check_update_ftr_reg(SYS_MPAMIDR_EL1, cpu,
info->reg_mpamidr, boot->reg_mpamidr);
}
@@ -494,8 +494,11 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0))
__cpuinfo_store_cpu_32bit(&info->aarch32);
- if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0))
- info->reg_mpamidr = read_cpuid(MPAMIDR_EL1);
+ /*
+ * info->mpamidr deferred to {init,update}_cpu_features because we
+ * don't want to read it (and trigger a trap on buggy firmware) if
+ * using an aa64pfr0_el1 override to unconditionally disable MPAM.
+ */
if (IS_ENABLED(CONFIG_ARM64_SME) &&
id_aa64pfr1_sme(info->reg_id_aa64pfr1)) {
@@ -127,6 +127,7 @@ static const struct ftr_set_desc pfr0 __prel64_initconst = {
.fields = {
FIELD("sve", ID_AA64PFR0_EL1_SVE_SHIFT, pfr0_sve_filter),
FIELD("el0", ID_AA64PFR0_EL1_EL0_SHIFT, NULL),
+ FIELD("mpam", ID_AA64PFR0_EL1_MPAM_SHIFT, NULL),
{}
},
};
@@ -246,6 +247,7 @@ static const struct {
{ "rodata=off", "arm64_sw.rodataoff=1" },
{ "arm64.nolva", "id_aa64mmfr2.varange=0" },
{ "arm64.no32bit_el0", "id_aa64pfr0.el0=1" },
+ { "arm64.nompam", "id_aa64pfr0.mpam=0" },
};
static int __init parse_hexdigit(const char *p, u64 *v)
As the message of the commit 09e6b306f3ba ("arm64: cpufeature: discover CPU support for MPAM") already states, if a buggy firmware fails to either enable MPAM or emulate the trap as if it were disabled, the kernel will just fail to boot. While upgrading the firmware should be the best solution, we have some hardware of which the vendor have made no response 2 months after we requested a firmware update. Allow overriding it so our devices don't become some e-waste. Cc: James Morse <james.morse@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> Cc: Mingcong Bai <jeffbai@aosc.io> Signed-off-by: Xi Ruoyao <xry111@xry111.site> --- [v1]->v2: - Handle the override and initialize EL2 mpam in finalise_el2_state - Move info->mpamidr assignment to {init,update}_cpu_features [v1]: https://lore.kernel.org/linux-arm-kernel/20250401055650.22542-1-xry111@xry111.site/ .../admin-guide/kernel-parameters.txt | 3 +++ arch/arm64/include/asm/el2_setup.h | 24 ++++++++----------- arch/arm64/kernel/cpufeature.c | 8 +++++-- arch/arm64/kernel/cpuinfo.c | 7 ++++-- arch/arm64/kernel/pi/idreg-override.c | 2 ++ 5 files changed, 26 insertions(+), 18 deletions(-)