From: eillon Add HDBSS (Hardware Dirty Bit State Structure) per-vCPU buffer management including allocation, freeing, and loading of HDBSS registers during vCPU load. This patch creates the foundational infrastructure: - struct vcpu_hdbss_state and enable_hdbss/hdbss_order in kvm_arch - kvm_dirty_bit.h header with alloc/free declarations - dirty_bit.c with alloc/free helpers - __load_hdbss() in VHE switch for register loading - vCPU create/destroy hooks for buffer lifecycle - sysreg definitions for HDBSS register manipulation - Makefile update for dirty_bit.o Signed-off-by: Eillon Signed-off-by: Tian Zheng --- arch/arm64/include/asm/kvm_dirty_bit.h | 16 ++++++++ arch/arm64/include/asm/kvm_host.h | 13 +++++++ arch/arm64/include/asm/sysreg.h | 11 ++++++ arch/arm64/kvm/Makefile | 1 + arch/arm64/kvm/arm.c | 7 ++++ arch/arm64/kvm/dirty_bit.c | 52 ++++++++++++++++++++++++++ arch/arm64/kvm/hyp/vhe/switch.c | 15 ++++++++ arch/arm64/kvm/mmu.c | 1 + arch/arm64/kvm/reset.c | 4 ++ 9 files changed, 120 insertions(+) create mode 100644 arch/arm64/include/asm/kvm_dirty_bit.h create mode 100644 arch/arm64/kvm/dirty_bit.c diff --git a/arch/arm64/include/asm/kvm_dirty_bit.h b/arch/arm64/include/asm/kvm_dirty_bit.h new file mode 100644 index 000000000000..84b12f0a10af --- /dev/null +++ b/arch/arm64/include/asm/kvm_dirty_bit.h @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2026 ARM Ltd. + * Author: Leonardo Bras + */ + +#ifndef __ARM64_KVM_DIRTY_BIT_H__ +#define __ARM64_KVM_DIRTY_BIT_H__ + +#include +#include + +int kvm_arm_vcpu_alloc_hdbss(struct kvm_vcpu *vcpu, unsigned int order); +void kvm_arm_vcpu_free_hdbss(struct kvm_vcpu *vcpu); + +#endif /* __ARM64_KVM_DIRTY_BIT_H__ */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index bae2c4f92ef5..c41ec6d9c45a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -420,6 +420,10 @@ struct kvm_arch { */ struct kvm_protected_vm pkvm; + /* HDBSS: per-VM dirty tracking state */ + bool enable_hdbss; + unsigned int hdbss_order; + #ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS /* Nested virtualization info */ struct dentry *debugfs_nv_dentry; @@ -838,6 +842,12 @@ struct vcpu_reset_state { bool reset; }; +struct vcpu_hdbss_state { + phys_addr_t base_phys; /* for memory free */ + u64 hdbssbr_el2; /* load directly */ + u64 hdbssprod_el2; /* save directly */ +}; + struct vncr_tlb; struct kvm_vcpu_arch { @@ -945,6 +955,9 @@ struct kvm_vcpu_arch { /* Hyp-readable copy of kvm_vcpu::pid */ pid_t pid; + + /* HDBSS registers info */ + struct vcpu_hdbss_state hdbss; }; /* diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 7aa08d59d494..1354a58c3316 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -1039,6 +1039,17 @@ #define GCS_CAP(x) ((((unsigned long)x) & GCS_CAP_ADDR_MASK) | \ GCS_CAP_VALID_TOKEN) + +/* + * Definitions for the HDBSS feature + */ +#define HDBSS_MAX_ORDER HDBSSBR_EL2_SZ_2MB + +#define HDBSSBR_EL2(baddr, sz) (((baddr) & HDBSSBR_EL2_BADDR_MASK) | \ + FIELD_PREP(HDBSSBR_EL2_SZ_MASK, sz)) + +#define HDBSSPROD_IDX(prod) FIELD_GET(HDBSSPROD_EL2_INDEX_MASK, prod) + /* * Definitions for GICv5 instructions */ diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile index 59612d2f277c..ec2749af64fa 100644 --- a/arch/arm64/kvm/Makefile +++ b/arch/arm64/kvm/Makefile @@ -18,6 +18,7 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \ guest.o debug.o reset.o sys_regs.o stacktrace.o \ vgic-sys-reg-v3.o fpsimd.o pkvm.o \ arch_timer.o trng.o vmid.o emulate-nested.o nested.o at.o \ + dirty_bit.o \ vgic/vgic.o vgic/vgic-init.o \ vgic/vgic-irqfd.o vgic/vgic-v2.o \ vgic/vgic-v3.o vgic/vgic-v4.o \ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 50adfff75be8..bf6688245d83 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include #include @@ -565,6 +566,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) if (err) kvm_vgic_vcpu_destroy(vcpu); + if (vcpu->kvm->arch.enable_hdbss) { + err = kvm_arm_vcpu_alloc_hdbss(vcpu, vcpu->kvm->arch.hdbss_order); + if (err) + kvm_vgic_vcpu_destroy(vcpu); + } + return err; } diff --git a/arch/arm64/kvm/dirty_bit.c b/arch/arm64/kvm/dirty_bit.c new file mode 100644 index 000000000000..6c7a6ef66b5a --- /dev/null +++ b/arch/arm64/kvm/dirty_bit.c @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2026 ARM Ltd. + * Author: Leonardo Bras + */ + +#include +#include +#include +#include +#include +#include + +int kvm_arm_vcpu_alloc_hdbss(struct kvm_vcpu *vcpu, unsigned int order) +{ + struct page *hdbss_pg = NULL; + + if (vcpu->arch.hdbss.hdbssbr_el2 || !system_supports_hdbss()) + return 0; + + if (order > HDBSS_MAX_ORDER) + return -EINVAL; + + hdbss_pg = alloc_pages(GFP_KERNEL_ACCOUNT, order); + if (!hdbss_pg) + return -ENOMEM; + + vcpu->arch.hdbss = (struct vcpu_hdbss_state) { + .base_phys = page_to_phys(hdbss_pg), + .hdbssbr_el2 = HDBSSBR_EL2(page_to_phys(hdbss_pg), order), + .hdbssprod_el2 = 0, + }; + + return 0; +} + +void kvm_arm_vcpu_free_hdbss(struct kvm_vcpu *vcpu) +{ + struct page *hdbss_pg; + + if (!vcpu->arch.hdbss.hdbssbr_el2) { + return; + } + + hdbss_pg = phys_to_page(vcpu->arch.hdbss.base_phys); + if (hdbss_pg) + __free_pages(hdbss_pg, + FIELD_GET(HDBSSBR_EL2_SZ_MASK, + vcpu->arch.hdbss.hdbssbr_el2)); + + vcpu->arch.hdbss.hdbssbr_el2 = 0; +} diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index bbe9cebd3d9d..fe72944bfd3d 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -213,6 +214,19 @@ static void __vcpu_put_deactivate_traps(struct kvm_vcpu *vcpu) local_irq_restore(flags); } +static void __load_hdbss(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; + + if (!kvm->arch.enable_hdbss) + return; + + write_sysreg_s(vcpu->arch.hdbss.hdbssbr_el2, SYS_HDBSSBR_EL2); + write_sysreg_s(vcpu->arch.hdbss.hdbssprod_el2, SYS_HDBSSPROD_EL2); + + isb(); +} + void kvm_vcpu_load_vhe(struct kvm_vcpu *vcpu) { host_data_ptr(host_ctxt)->__hyp_running_vcpu = vcpu; @@ -220,6 +234,7 @@ void kvm_vcpu_load_vhe(struct kvm_vcpu *vcpu) __vcpu_load_switch_sysregs(vcpu); __vcpu_load_activate_traps(vcpu); __load_stage2(vcpu->arch.hw_mmu); + __load_hdbss(vcpu); } void kvm_vcpu_put_vhe(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 346efed6e605..83251d95bf3f 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index b963fd975aac..d8104bcbd9ff 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include @@ -161,6 +162,9 @@ void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu) free_page((unsigned long)vcpu->arch.ctxt.vncr_array); kfree(vcpu->arch.vncr_tlb); kfree(vcpu->arch.ccsidr); + + if (vcpu->kvm->arch.enable_hdbss) + kvm_arm_vcpu_free_hdbss(vcpu); } static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu) -- 2.33.0