Message-ID: <CAAhV-H5MEEACwp-NAPMWDhv31YT9cqJE6o8Z_O3UtHepyKF81g@mail.gmail.com>
Date:   Sun, 17 Sep 2023 12:21:44 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Tianrui Zhao <zhaotianrui@...ngson.cn>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        WANG Xuerui <kernel@...0n.name>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        loongarch@...ts.linux.dev, Jens Axboe <axboe@...nel.dk>,
        Mark Brown <broonie@...nel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Oliver Upton <oliver.upton@...ux.dev>, maobibo@...ngson.cn,
        Xi Ruoyao <xry111@...111.site>
Subject: Re: [PATCH v21 02/29] LoongArch: KVM: Implement kvm module related interface

Hi, Tianrui,

On Fri, Sep 15, 2023 at 9:50 AM Tianrui Zhao <zhaotianrui@...ngson.cn> wrote:
>
> Implement LoongArch kvm module init, module exit interface,
> using kvm context to save the vpid info and vcpu world switch
> interface pointer.
>
> Reviewed-by: Bibo Mao <maobibo@...ngson.cn>
> Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
> ---
>  arch/loongarch/kvm/main.c | 367 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 367 insertions(+)
>  create mode 100644 arch/loongarch/kvm/main.c
>
> diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
> new file mode 100644
> index 0000000000..0deb9273d8
> --- /dev/null
> +++ b/arch/loongarch/kvm/main.c
> @@ -0,0 +1,367 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/kvm_host.h>
> +#include <asm/cacheflush.h>
> +#include <asm/cpufeature.h>
> +#include <asm/kvm_csr.h>
> +#include "trace.h"
> +
> +static struct kvm_context __percpu *vmcs;
> +struct kvm_world_switch *kvm_loongarch_ops;
> +unsigned long vpid_mask;
> +static int gcsr_flag[CSR_MAX_NUMS];
> +
> +int get_gcsr_flag(int csr)
> +{
> +       if (csr < CSR_MAX_NUMS)
> +               return gcsr_flag[csr];
> +
> +       return INVALID_GCSR;
> +}
> +
> +static inline void set_gcsr_sw_flag(int csr)
> +{
> +       if (csr < CSR_MAX_NUMS)
> +               gcsr_flag[csr] |= SW_GCSR;
> +}
> +
> +static inline void set_gcsr_hw_flag(int csr)
> +{
> +       if (csr < CSR_MAX_NUMS)
> +               gcsr_flag[csr] |= HW_GCSR;
> +}
> +
> +/*
> + * The default value of gcsr_flag[CSR] is 0, and we use this
> + * function to set the flag to 1(SW_GCSR) or 2(HW_GCSR) if the
> + * gcsr is software or hardware. It will be used by get/set_gcsr,
> + * if gcsr_flag is HW we should use gcsrrd/gcsrwr to access it,
> + * else use sw csr to emulate it.
> + */
> +static void kvm_init_gcsr_flag(void)
> +{
> +       set_gcsr_hw_flag(LOONGARCH_CSR_CRMD);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PRMD);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_EUEN);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_MISC);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_ECFG);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_ESTAT);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_ERA);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_BADV);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_BADI);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_EENTRY);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBIDX);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBEHI);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBELO0);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBELO1);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_ASID);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PGDL);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PGDH);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PWCTL0);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PWCTL1);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_STLBPGSIZE);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_RVACFG);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_CPUID);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PRCFG1);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PRCFG2);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_PRCFG3);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS0);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS1);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS2);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS3);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS4);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS5);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS6);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_KS7);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TMID);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TCFG);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TVAL);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_CNTC);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_LLBCTL);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRENTRY);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRBADV);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRERA);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRSAVE);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRELO0);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRELO1);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBREHI);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_TLBRPRMD);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN0);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN1);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN2);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN3);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_MWPS);
> +       set_gcsr_hw_flag(LOONGARCH_CSR_FWPS);
> +
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IMPCTL1);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IMPCTL2);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MERRCTL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MERRINFO1);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MERRINFO2);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MERRENTRY);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MERRERA);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MERRSAVE);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_CTAG);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DEBUG);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DERA);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DESAVE);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PRCFG1);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PRCFG2);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PRCFG3);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PGD);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_TINTCLR);
> +
> +       set_gcsr_sw_flag(LOONGARCH_CSR_FWPS);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_FWPC);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MWPS);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_MWPC);
> +
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB0ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB0MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB0CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB0ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB1ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB1MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB1CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB1ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB2ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB2MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB2CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB2ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB3ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB3MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB3CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB3ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB4ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB4MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB4CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB4ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB5ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB5MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB5CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB5ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB6ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB6MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB6CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB6ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB7ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB7MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB7CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_DB7ASID);
> +
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB0ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB0MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB0CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB0ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB1ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB1MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB1CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB1ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB2ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB2MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB2CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB2ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB3ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB3MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB3CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB3ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB4ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB4MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB4CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB4ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB5ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB5MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB5CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB5ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB6ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB6MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB6CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB6ASID);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB7ADDR);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB7MASK);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB7CTRL);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_IB7ASID);
> +
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL0);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR0);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL1);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR1);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL2);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR2);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL3);
> +       set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR3);
> +}
> +
> +static void kvm_update_vpid(struct kvm_vcpu *vcpu, int cpu)
> +{
> +       struct kvm_context *context;
> +       unsigned long vpid;
> +
> +       context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
> +       vpid = context->vpid_cache + 1;
> +       if (!(vpid & vpid_mask)) {
> +               /* finish round of 64 bit loop */
> +               if (unlikely(!vpid))
> +                       vpid = vpid_mask + 1;
> +
> +               /* vpid 0 reserved for root */
> +               ++vpid;
> +
> +               /* start new vpid cycle */
> +               kvm_flush_tlb_all();
> +       }
> +
> +       context->vpid_cache = vpid;
> +       vcpu->arch.vpid = vpid;
> +}
> +
> +void kvm_check_vpid(struct kvm_vcpu *vcpu)
> +{
> +       struct kvm_context *context;
> +       bool migrated;
> +       unsigned long ver, old, vpid;
> +       int cpu;
> +
> +       cpu = smp_processor_id();
> +       /*
> +        * Are we entering guest context on a different CPU to last time?
> +        * If so, the vCPU's guest TLB state on this CPU may be stale.
> +        */
> +       context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
> +       migrated = (vcpu->cpu != cpu);
> +
> +       /*
> +        * Check if our vpid is of an older version
> +        *
> +        * We also discard the stored vpid if we've executed on
> +        * another CPU, as the guest mappings may have changed without
> +        * hypervisor knowledge.
> +        */
> +       ver = vcpu->arch.vpid & ~vpid_mask;
> +       old = context->vpid_cache  & ~vpid_mask;
> +       if (migrated || (ver != old)) {
> +               kvm_update_vpid(vcpu, cpu);
> +               trace_kvm_vpid_change(vcpu, vcpu->arch.vpid);
> +               vcpu->cpu = cpu;
> +       }
> +
> +       /* Restore GSTAT(0x50).vpid */
> +       vpid = (vcpu->arch.vpid & vpid_mask) << CSR_GSTAT_GID_SHIFT;
> +       change_csr_gstat(vpid_mask << CSR_GSTAT_GID_SHIFT, vpid);
> +}
> +
> +static int kvm_loongarch_env_init(void)
> +{
> +       struct kvm_context *context;
> +       int cpu, order;
> +       void *addr;
> +
> +       vmcs = alloc_percpu(struct kvm_context);
> +       if (!vmcs) {
> +               pr_err("kvm: failed to allocate percpu kvm_context\n");
> +               return -ENOMEM;
> +       }
> +
> +       kvm_loongarch_ops = kzalloc(sizeof(*kvm_loongarch_ops), GFP_KERNEL);
> +       if (!kvm_loongarch_ops) {
> +               free_percpu(vmcs);
> +               vmcs = NULL;
> +               return -ENOMEM;
> +       }
> +       /*
> +        * There will be problem in world switch code if there
> +        * is page fault reenter, since pgd register is shared
> +        * between root kernel and kvm hypervisor. World switch
> +        * entry need be unmapped area, cannot be tlb mapped area.
> +        * In future if hw pagetable walking is supported, or there
> +        * is separate pgd registers between root kernel and kvm
> +        * hypervisor, copying about world switch code will not be used.
> +        */
> +
> +       order = get_order(kvm_vector_size + kvm_enter_guest_size);
> +       addr = (void *)__get_free_pages(GFP_KERNEL, order);
> +       if (!addr) {
> +               free_percpu(vmcs);
> +               vmcs = NULL;
> +               kfree(kvm_loongarch_ops);
> +               kvm_loongarch_ops = NULL;
> +               return -ENOMEM;
> +       }
> +
> +       memcpy(addr, kvm_vector_entry, kvm_vector_size);
> +       memcpy(addr + kvm_vector_size, kvm_enter_guest, kvm_enter_guest_size);
Why memcpy? In our internal repo, we use kvm_vector_entry and
kvm_enter_guest directly. The long comments above make me nervous
because Loongson-3A6000 already supports hardware pagetable walker.

Huacai

> +       flush_icache_range((unsigned long)addr, (unsigned long)addr +
> +                               kvm_vector_size + kvm_enter_guest_size);
> +       kvm_loongarch_ops->guest_eentry = addr;
> +       kvm_loongarch_ops->enter_guest = addr + kvm_vector_size;
> +       kvm_loongarch_ops->page_order = order;
> +
> +       vpid_mask = read_csr_gstat();
> +       vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >> CSR_GSTAT_GIDBIT_SHIFT;
> +       if (vpid_mask)
> +               vpid_mask = GENMASK(vpid_mask - 1, 0);
> +
> +       for_each_possible_cpu(cpu) {
> +               context = per_cpu_ptr(vmcs, cpu);
> +               context->vpid_cache = vpid_mask + 1;
> +               context->last_vcpu = NULL;
> +       }
> +
> +       kvm_init_fault();
> +       kvm_init_gcsr_flag();
> +
> +       return 0;
> +}
> +
> +static void kvm_loongarch_env_exit(void)
> +{
> +       unsigned long addr;
> +
> +       if (vmcs)
> +               free_percpu(vmcs);
> +
> +       if (kvm_loongarch_ops) {
> +               if (kvm_loongarch_ops->guest_eentry) {
> +                       addr = (unsigned long)kvm_loongarch_ops->guest_eentry;
> +                       free_pages(addr, kvm_loongarch_ops->page_order);
> +               }
> +               kfree(kvm_loongarch_ops);
> +       }
> +}
> +
> +static int kvm_loongarch_init(void)
> +{
> +       int r;
> +
> +       if (!cpu_has_lvz) {
> +               kvm_info("hardware virtualization not available\n");
> +               return -ENODEV;
> +       }
> +       r = kvm_loongarch_env_init();
> +       if (r)
> +               return r;
> +
> +       return kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
> +}
> +
> +static void kvm_loongarch_exit(void)
> +{
> +       kvm_exit();
> +       kvm_loongarch_env_exit();
> +}
> +
> +module_init(kvm_loongarch_init);
> +module_exit(kvm_loongarch_exit);
> +
> +#ifdef MODULE
> +static const struct cpu_feature loongarch_kvm_feature[] = {
> +       { .feature = cpu_feature(LOONGARCH_LVZ) },
> +       {},
> +};
> +MODULE_DEVICE_TABLE(cpu, loongarch_kvm_feature);
> +#endif
> --
> 2.39.1
>

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