From: James Morse james.morse@arm.com
maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8T2RT
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/...
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While we trap the guest's attempts to read/write the MPAM control registers, these remain in effect. guest-EL0 uses KVM's user-space's configuration, as the value is left in the register, and guest-EL1 uses either the host kernel's configuration, or in the case of VHE, the unknown reset value of MPAM1_EL1.
On nVHE systems, EL2 continues to use partid-0 for world-switch, even when the host may have configured its kernel threads to use a different partid. 0 may have been assigned to another task.
We want to force the guest-EL1 to use KVM's user-space's MPAM configuration.
On a nVHE system, copy the EL1 MPAM register to EL2. This ensures world-switch uses the same partid as the kernel thread does on the host.
When loading the guests EL1 registers, copy the VMM's EL0 partid to the EL1 register. When restoring the hosts registers, the partid previously copied to EL2 can be used to restore EL1.
For VHE systems, we can skip restoring the EL1 register for the host, as it is out-of-context once HCR_EL2.TGE is set.
This is done outside the usual sysreg save/restore as the values can change behind KVMs back, so should not be stored in the guest context.
Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Zeng Heng zengheng4@huawei.com --- arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 27 ++++++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/switch.c | 11 +++++++++ arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 1 + 3 files changed, 39 insertions(+)
diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h index bb6b571ec627..d6cfb3dc7f7c 100644 --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h @@ -15,6 +15,7 @@ #include <asm/kvm_emulate.h> #include <asm/kvm_hyp.h> #include <asm/kvm_mmu.h> +#include <asm/mpam.h>
static inline void __sysreg_save_common_state(struct kvm_cpu_context *ctxt) { @@ -243,4 +244,30 @@ static inline void __sysreg32_restore_state(struct kvm_vcpu *vcpu) write_sysreg(__vcpu_sys_reg(vcpu, DBGVCR32_EL2), dbgvcr32_el2); }
+/* + * The _EL0 value was written by the host's context switch, copy this into the + * guest's EL1. + */ +static inline void __mpam_guest_load(void) +{ + if (IS_ENABLED(CONFIG_ARM64_MPAM) && mpam_cpus_have_feature()) + write_sysreg_el1(read_sysreg_s(SYS_MPAM0_EL1), SYS_MPAM1); +} + +/* + * Copy the _EL2 register back to _EL1, clearing any trap bits EL2 may have set. + * nVHE world-switch copies the _EL1 register to _EL2. A VHE host writes to the + * _EL2 register as it is aliased by the hardware when TGE is set. + */ +static inline void __mpam_guest_put(void) +{ + u64 val, mask = MPAM_SYSREG_PMG_D | MPAM_SYSREG_PMG_I | + MPAM_SYSREG_PARTID_D | MPAM_SYSREG_PARTID_I; + + if (IS_ENABLED(CONFIG_ARM64_MPAM) && mpam_cpus_have_feature()) { + val = FIELD_GET(mask, read_sysreg_s(SYS_MPAM2_EL2)); + write_sysreg_el1(val, SYS_MPAM1); + } +} + #endif /* __ARM64_KVM_HYP_SYSREG_SR_H__ */ diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index c353a06ee7e6..c2118f658e22 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -242,6 +242,13 @@ static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code) } }
+/* Use the host thread's partid and pmg for world switch */ +static void __mpam_copy_el1_to_el2(void) +{ + if (IS_ENABLED(CONFIG_ARM64_MPAM) && mpam_cpus_have_feature()) + write_sysreg_s(read_sysreg_s(SYS_MPAM1_EL1), SYS_MPAM2_EL2); +} + /* Switch to the guest for legacy non-VHE systems */ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) { @@ -251,6 +258,8 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) bool pmu_switch_needed; u64 exit_code;
+ __mpam_copy_el1_to_el2(); + /* * Having IRQs masked via PMR when entering the guest means the GIC * will not signal the CPU of interrupts of lower priority, and the @@ -310,6 +319,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) __timer_enable_traps(vcpu);
__debug_switch_to_guest(vcpu); + __mpam_guest_load();
do { /* Jump in the fire! */ @@ -320,6 +330,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
__sysreg_save_state_nvhe(guest_ctxt); __sysreg32_save_state(vcpu); + __mpam_guest_put(); __timer_disable_traps(vcpu); __hyp_vgic_save_state(vcpu);
diff --git a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c index b35a178e7e0d..6b407cd3230d 100644 --- a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c +++ b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c @@ -90,6 +90,7 @@ void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu) __sysreg32_restore_state(vcpu); __sysreg_restore_user_state(guest_ctxt); __sysreg_restore_el1_state(guest_ctxt); + __mpam_guest_load();
vcpu_set_flag(vcpu, SYSREGS_ON_CPU);