| Message ID | 20250205164630.1706058-1-tabba@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v1] arm64: head.S: Do not trap access to MPAMSM_EL1 | expand |
On Wed, 05 Feb 2025 16:46:27 +0000, Fuad Tabba <tabba@google.com> wrote: > > Bit 50 of MPAM2_EL2, EnMPAMSM, traps access to MPAMSM_EL1 when 0, > as per ARM ARM DDI DDI0487L.a, section D24.12.3. Therefore, > ensure it is set to 1 for the host to disable the traps. But what makes use of this register in the kernel? I can't find any trace of it in 6.14-rc1. Thanks, M.
diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h index 25e162651750..fb4da155d994 100644 --- a/arch/arm64/include/asm/el2_setup.h +++ b/arch/arm64/include/asm/el2_setup.h @@ -254,8 +254,10 @@ 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 + mov_q x0, MPAM2_HOST_FLAGS + msr_s SYS_MPAM2_EL2, x0 // use the default partition // and disable lower traps + // don't trap access to MPAMSM_EL1 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 diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 8d94a6c0ed5c..78d46d52b3da 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -147,6 +147,9 @@ #define VTCR_EL2_T0SZ(x) TCR_T0SZ(x) +/* MPAM2_EL2 for the host to ensure not to trap access to MPAMSM_EL1. */ +#define MPAM2_HOST_FLAGS MPAM2_EL2_EnMPAMSM + /* * We configure the Stage-2 page tables to always restrict the IPA space to be * 40 bits wide (T0SZ = 24). Systems with a PARange smaller than 40 bits are diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index f838a45665f2..44b4995258e8 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -227,7 +227,7 @@ static inline void __deactivate_traps_mpam(void) if (!system_supports_mpam()) return; - write_sysreg_s(0, SYS_MPAM2_EL2); + write_sysreg_s(MPAM2_HOST_FLAGS, SYS_MPAM2_EL2); if (system_supports_mpam_hcr()) write_sysreg_s(MPAMHCR_HOST_FLAGS, SYS_MPAMHCR_EL2);
Bit 50 of MPAM2_EL2, EnMPAMSM, traps access to MPAMSM_EL1 when 0, as per ARM ARM DDI DDI0487L.a, section D24.12.3. Therefore, ensure it is set to 1 for the host to disable the traps. Fixes: 31ff96c38ea3 ("KVM: arm64: Fix missing traps of guest accesses to the MPAM registers") Fixes: 23b33d1e168c ("arm64: head.S: Initialise MPAM EL2 registers and disable traps") Signed-off-by: Fuad Tabba <tabba@google.com> --- arch/arm64/include/asm/el2_setup.h | 4 +++- arch/arm64/include/asm/kvm_arm.h | 3 +++ arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +- 3 files changed, 7 insertions(+), 2 deletions(-) base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b