From: Anup Patel anup.patel@wdc.com
euleros inclusion category: feature feature: initial KVM RISC-V support bugzilla: 46845 CVE: NA
We implement a simple VMID allocator for Guests/VMs which: 1. Detects number of VMID bits at boot-time 2. Uses atomic number to track VMID version and increments VMID version whenever we run-out of VMIDs 3. Flushes Guest TLBs on all host CPUs whenever we run-out of VMIDs 4. Force updates HW Stage2 VMID for each Guest VCPU whenever VMID changes using VCPU request KVM_REQ_UPDATE_HGATP
Reference: https://gitee.com/openeuler/kernel/issues/I26X9V Signed-off-by: Anup Patel anup.patel@wdc.com Acked-by: Paolo Bonzini pbonzini@redhat.com Reviewed-by: Paolo Bonzini pbonzini@redhat.com Reviewed-by: Alexander Graf graf@amazon.com --- arch/riscv/include/asm/kvm_host.h | 24 ++++++ arch/riscv/kvm/Makefile | 3 +- arch/riscv/kvm/main.c | 4 + arch/riscv/kvm/tlb.S | 74 ++++++++++++++++++ arch/riscv/kvm/vcpu.c | 9 +++ arch/riscv/kvm/vm.c | 6 ++ arch/riscv/kvm/vmid.c | 120 ++++++++++++++++++++++++++++++ 7 files changed, 239 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/kvm/tlb.S create mode 100644 arch/riscv/kvm/vmid.c
diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h index 47655fe2f..08681e58c 100644 --- a/arch/riscv/include/asm/kvm_host.h +++ b/arch/riscv/include/asm/kvm_host.h @@ -27,6 +27,7 @@ #define KVM_REQ_SLEEP \ KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(1) +#define KVM_REQ_UPDATE_HGATP KVM_ARCH_REQ(2)
struct kvm_vm_stat { ulong remote_tlb_flush; @@ -49,7 +50,19 @@ struct kvm_vcpu_stat { struct kvm_arch_memory_slot { };
+struct kvm_vmid { + /* + * Writes to vmid_version and vmid happen with vmid_lock held + * whereas reads happen without any lock held. + */ + unsigned long vmid_version; + unsigned long vmid; +}; + struct kvm_arch { + /* stage2 vmid */ + struct kvm_vmid vmid; + /* stage2 page table */ pgd_t *pgd; phys_addr_t pgd_phys; @@ -180,6 +193,11 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
+void __kvm_riscv_hfence_gvma_vmid_gpa(unsigned long gpa, unsigned long vmid); +void __kvm_riscv_hfence_gvma_vmid(unsigned long vmid); +void __kvm_riscv_hfence_gvma_gpa(unsigned long gpa); +void __kvm_riscv_hfence_gvma_all(void); + int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, gpa_t gpa, unsigned long hva, @@ -189,6 +207,12 @@ int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm); void kvm_riscv_stage2_free_pgd(struct kvm *kvm); void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
+void kvm_riscv_stage2_vmid_detect(void); +unsigned long kvm_riscv_stage2_vmid_bits(void); +int kvm_riscv_stage2_vmid_init(struct kvm *kvm); +bool kvm_riscv_stage2_vmid_ver_changed(struct kvm_vmid *vmid); +void kvm_riscv_stage2_vmid_update(struct kvm_vcpu *vcpu); + void __kvm_riscv_unpriv_trap(void);
unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu, diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile index 54991cc55..b32f60edf 100644 --- a/arch/riscv/kvm/Makefile +++ b/arch/riscv/kvm/Makefile @@ -9,6 +9,7 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
kvm-objs := $(common-objs-y)
-kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o +kvm-objs += main.o vm.o vmid.o tlb.o mmu.o +kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o
obj-$(CONFIG_KVM) += kvm.o diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c index 47926f0c1..49a4941e3 100644 --- a/arch/riscv/kvm/main.c +++ b/arch/riscv/kvm/main.c @@ -79,8 +79,12 @@ int kvm_arch_init(void *opaque) return -ENODEV; }
+ kvm_riscv_stage2_vmid_detect(); + kvm_info("hypervisor extension available\n");
+ kvm_info("VMID %ld bits available\n", kvm_riscv_stage2_vmid_bits()); + return 0; }
diff --git a/arch/riscv/kvm/tlb.S b/arch/riscv/kvm/tlb.S new file mode 100644 index 000000000..c858570f0 --- /dev/null +++ b/arch/riscv/kvm/tlb.S @@ -0,0 +1,74 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019 Western Digital Corporation or its affiliates. + * + * Authors: + * Anup Patel anup.patel@wdc.com + */ + +#include <linux/linkage.h> +#include <asm/asm.h> + + .text + .altmacro + .option norelax + + /* + * Instruction encoding of hfence.gvma is: + * HFENCE.GVMA rs1, rs2 + * HFENCE.GVMA zero, rs2 + * HFENCE.GVMA rs1 + * HFENCE.GVMA + * + * rs1!=zero and rs2!=zero ==> HFENCE.GVMA rs1, rs2 + * rs1==zero and rs2!=zero ==> HFENCE.GVMA zero, rs2 + * rs1!=zero and rs2==zero ==> HFENCE.GVMA rs1 + * rs1==zero and rs2==zero ==> HFENCE.GVMA + * + * Instruction encoding of HFENCE.GVMA is: + * 0110001 rs2(5) rs1(5) 000 00000 1110011 + */ + +ENTRY(__kvm_riscv_hfence_gvma_vmid_gpa) + /* + * rs1 = a0 (GPA) + * rs2 = a1 (VMID) + * HFENCE.GVMA a0, a1 + * 0110001 01011 01010 000 00000 1110011 + */ + .word 0x62b50073 + ret +ENDPROC(__kvm_riscv_hfence_gvma_vmid_gpa) + +ENTRY(__kvm_riscv_hfence_gvma_vmid) + /* + * rs1 = zero + * rs2 = a0 (VMID) + * HFENCE.GVMA zero, a0 + * 0110001 01010 00000 000 00000 1110011 + */ + .word 0x62a00073 + ret +ENDPROC(__kvm_riscv_hfence_gvma_vmid) + +ENTRY(__kvm_riscv_hfence_gvma_gpa) + /* + * rs1 = a0 (GPA) + * rs2 = zero + * HFENCE.GVMA a0 + * 0110001 00000 01010 000 00000 1110011 + */ + .word 0x62050073 + ret +ENDPROC(__kvm_riscv_hfence_gvma_gpa) + +ENTRY(__kvm_riscv_hfence_gvma_all) + /* + * rs1 = zero + * rs2 = zero + * HFENCE.GVMA + * 0110001 00000 00000 000 00000 1110011 + */ + .word 0x62000073 + ret +ENDPROC(__kvm_riscv_hfence_gvma_all) diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index 43962a25f..7192b6edd 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -637,6 +637,12 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu)) kvm_riscv_reset_vcpu(vcpu); + + if (kvm_check_request(KVM_REQ_UPDATE_HGATP, vcpu)) + kvm_riscv_stage2_update_hgatp(vcpu); + + if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) + __kvm_riscv_hfence_gvma_all(); } }
@@ -682,6 +688,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) /* Check conditions before entering the guest */ cond_resched();
+ kvm_riscv_stage2_vmid_update(vcpu); + kvm_riscv_check_vcpu_requests(vcpu);
preempt_disable(); @@ -718,6 +726,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) kvm_riscv_update_hvip(vcpu);
if (ret <= 0 || + kvm_riscv_stage2_vmid_ver_changed(&vcpu->kvm->arch.vmid) || kvm_request_pending(vcpu)) { vcpu->mode = OUTSIDE_GUEST_MODE; local_irq_enable(); diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c index 496a86a74..282d67617 100644 --- a/arch/riscv/kvm/vm.c +++ b/arch/riscv/kvm/vm.c @@ -26,6 +26,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) if (r) return r;
+ r = kvm_riscv_stage2_vmid_init(kvm); + if (r) { + kvm_riscv_stage2_free_pgd(kvm); + return r; + } + return 0; }
diff --git a/arch/riscv/kvm/vmid.c b/arch/riscv/kvm/vmid.c new file mode 100644 index 000000000..2c6253b29 --- /dev/null +++ b/arch/riscv/kvm/vmid.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 Western Digital Corporation or its affiliates. + * + * Authors: + * Anup Patel anup.patel@wdc.com + */ + +#include <linux/bitops.h> +#include <linux/cpumask.h> +#include <linux/errno.h> +#include <linux/err.h> +#include <linux/module.h> +#include <linux/kvm_host.h> +#include <asm/csr.h> +#include <asm/sbi.h> + +static unsigned long vmid_version = 1; +static unsigned long vmid_next; +static unsigned long vmid_bits; +static DEFINE_SPINLOCK(vmid_lock); + +void kvm_riscv_stage2_vmid_detect(void) +{ + unsigned long old; + + /* Figure-out number of VMID bits in HW */ + old = csr_read(CSR_HGATP); + csr_write(CSR_HGATP, old | HGATP_VMID_MASK); + vmid_bits = csr_read(CSR_HGATP); + vmid_bits = (vmid_bits & HGATP_VMID_MASK) >> HGATP_VMID_SHIFT; + vmid_bits = fls_long(vmid_bits); + csr_write(CSR_HGATP, old); + + /* We polluted local TLB so flush all guest TLB */ + __kvm_riscv_hfence_gvma_all(); + + /* We don't use VMID bits if they are not sufficient */ + if ((1UL << vmid_bits) < num_possible_cpus()) + vmid_bits = 0; +} + +unsigned long kvm_riscv_stage2_vmid_bits(void) +{ + return vmid_bits; +} + +int kvm_riscv_stage2_vmid_init(struct kvm *kvm) +{ + /* Mark the initial VMID and VMID version invalid */ + kvm->arch.vmid.vmid_version = 0; + kvm->arch.vmid.vmid = 0; + + return 0; +} + +bool kvm_riscv_stage2_vmid_ver_changed(struct kvm_vmid *vmid) +{ + if (!vmid_bits) + return false; + + return unlikely(READ_ONCE(vmid->vmid_version) != + READ_ONCE(vmid_version)); +} + +void kvm_riscv_stage2_vmid_update(struct kvm_vcpu *vcpu) +{ + int i; + struct kvm_vcpu *v; + struct cpumask hmask; + struct kvm_vmid *vmid = &vcpu->kvm->arch.vmid; + + if (!kvm_riscv_stage2_vmid_ver_changed(vmid)) + return; + + spin_lock(&vmid_lock); + + /* + * We need to re-check the vmid_version here to ensure that if + * another vcpu already allocated a valid vmid for this vm. + */ + if (!kvm_riscv_stage2_vmid_ver_changed(vmid)) { + spin_unlock(&vmid_lock); + return; + } + + /* First user of a new VMID version? */ + if (unlikely(vmid_next == 0)) { + WRITE_ONCE(vmid_version, READ_ONCE(vmid_version) + 1); + vmid_next = 1; + + /* + * We ran out of VMIDs so we increment vmid_version and + * start assigning VMIDs from 1. + * + * This also means existing VMIDs assignement to all Guest + * instances is invalid and we have force VMID re-assignement + * for all Guest instances. The Guest instances that were not + * running will automatically pick-up new VMIDs because will + * call kvm_riscv_stage2_vmid_update() whenever they enter + * in-kernel run loop. For Guest instances that are already + * running, we force VM exits on all host CPUs using IPI and + * flush all Guest TLBs. + */ + riscv_cpuid_to_hartid_mask(cpu_online_mask, &hmask); + sbi_remote_hfence_gvma(cpumask_bits(&hmask), 0, 0); + } + + vmid->vmid = vmid_next; + vmid_next++; + vmid_next &= (1 << vmid_bits) - 1; + + WRITE_ONCE(vmid->vmid_version, READ_ONCE(vmid_version)); + + spin_unlock(&vmid_lock); + + /* Request stage2 page table update for all VCPUs */ + kvm_for_each_vcpu(i, v, vcpu->kvm) + kvm_make_request(KVM_REQ_UPDATE_HGATP, v); +}