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References: <20230112140304.1830648-1-apatel@ventanamicro.com>
 <20230112140304.1830648-5-apatel@ventanamicro.com> <20230126164128.p3blvlwegizmh2ca@orel>
In-Reply-To: <20230126164128.p3blvlwegizmh2ca@orel>
From:   Anup Patel <apatel@ventanamicro.com>
Date:   Fri, 27 Jan 2023 20:00:59 +0530
Message-ID: <CAK9=C2XbzKKLtF0Z6tPJ8Hf4=Ze6R+9=hBHtuxpLX-4fh_5-kg@mail.gmail.com>
Subject: Re: [PATCH 4/7] RISC-V: KVM: Initial skeletal support for AIA
To:     Andrew Jones <ajones@ventanamicro.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Atish Patra <atishp@atishpatra.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Anup Patel <anup@brainfault.org>, kvm@vger.kernel.org,
        kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org
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Precedence: bulk

On Thu, Jan 26, 2023 at 10:11 PM Andrew Jones <ajones@ventanamicro.com> wrote:
>
> On Thu, Jan 12, 2023 at 07:33:01PM +0530, Anup Patel wrote:
> > To incrementally implement AIA support, we first add minimal skeletal
> > support which only compiles and detects AIA hardware support at the
> > boot-time but does not provide any functionality.
> >
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > ---
> >  arch/riscv/include/asm/kvm_aia.h  | 109 ++++++++++++++++++++++++++++++
> >  arch/riscv/include/asm/kvm_host.h |   7 ++
> >  arch/riscv/kvm/Makefile           |   1 +
> >  arch/riscv/kvm/aia.c              |  66 ++++++++++++++++++
> >  arch/riscv/kvm/main.c             |  13 ++++
> >  arch/riscv/kvm/vcpu.c             |  40 ++++++++++-
> >  arch/riscv/kvm/vcpu_insn.c        |   4 +-
> >  arch/riscv/kvm/vm.c               |   4 ++
> >  8 files changed, 240 insertions(+), 4 deletions(-)
> >  create mode 100644 arch/riscv/include/asm/kvm_aia.h
> >  create mode 100644 arch/riscv/kvm/aia.c
> >
> > diff --git a/arch/riscv/include/asm/kvm_aia.h b/arch/riscv/include/asm/kvm_aia.h
> > new file mode 100644
> > index 000000000000..52b5e8aefb30
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/kvm_aia.h
> > @@ -0,0 +1,109 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > + * Copyright (C) 2022 Ventana Micro Systems Inc.
> > + *
> > + * Authors:
> > + *   Anup Patel <apatel@ventanamicro.com>
> > + */
> > +
> > +#ifndef __KVM_RISCV_AIA_H
> > +#define __KVM_RISCV_AIA_H
> > +
> > +#include <linux/jump_label.h>
> > +#include <linux/kvm_types.h>
> > +
> > +struct kvm_aia {
> > +     /* In-kernel irqchip created */
> > +     bool            in_kernel;
> > +
> > +     /* In-kernel irqchip initialized */
> > +     bool            initialized;
> > +};
> > +
> > +struct kvm_vcpu_aia {
> > +};
> > +
> > +#define kvm_riscv_aia_initialized(k) (!!((k)->arch.aia.initialized))
> > +
> > +#define irqchip_in_kernel(k)         (!!((k)->arch.aia.in_kernel))
>
> No need for the '!!' operator in the above two defines since in both
> cases the type it's operating on is bool.

Okay, I will update.

>
> > +
> > +DECLARE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
> > +#define kvm_riscv_aia_available() \
> > +     static_branch_unlikely(&kvm_riscv_aia_available)
> > +
> > +static inline void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +static inline void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +static inline bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu,
> > +                                                  u64 mask)
> > +{
> > +     return false;
> > +}
> > +
> > +static inline void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +static inline void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu)
> > +{
> > +}
> > +
> > +static inline void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +static inline int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
> > +                                          unsigned long reg_num,
> > +                                          unsigned long *out_val)
> > +{
> > +     *out_val = 0;
> > +     return 0;
> > +}
> > +
> > +static inline int kvm_riscv_vcpu_aia_set_csr(struct kvm_vcpu *vcpu,
> > +                                          unsigned long reg_num,
> > +                                          unsigned long val)
> > +{
> > +     return 0;
> > +}
> > +
> > +#define KVM_RISCV_VCPU_AIA_CSR_FUNCS
> > +
> > +static inline int kvm_riscv_vcpu_aia_update(struct kvm_vcpu *vcpu)
> > +{
> > +     return 1;
> > +}
> > +
> > +static inline void kvm_riscv_vcpu_aia_reset(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +static inline int kvm_riscv_vcpu_aia_init(struct kvm_vcpu *vcpu)
> > +{
> > +     return 0;
> > +}
> > +
> > +static inline void kvm_riscv_vcpu_aia_deinit(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +static inline void kvm_riscv_aia_init_vm(struct kvm *kvm)
> > +{
> > +}
> > +
> > +static inline void kvm_riscv_aia_destroy_vm(struct kvm *kvm)
> > +{
> > +}
> > +
> > +void kvm_riscv_aia_enable(void);
> > +void kvm_riscv_aia_disable(void);
> > +int kvm_riscv_aia_init(void);
> > +void kvm_riscv_aia_exit(void);
> > +
> > +#endif
> > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > index 93f43a3e7886..b71f0e639b39 100644
> > --- a/arch/riscv/include/asm/kvm_host.h
> > +++ b/arch/riscv/include/asm/kvm_host.h
> > @@ -14,6 +14,7 @@
> >  #include <linux/kvm_types.h>
> >  #include <linux/spinlock.h>
> >  #include <asm/hwcap.h>
> > +#include <asm/kvm_aia.h>
> >  #include <asm/kvm_vcpu_fp.h>
> >  #include <asm/kvm_vcpu_insn.h>
> >  #include <asm/kvm_vcpu_sbi.h>
> > @@ -93,6 +94,9 @@ struct kvm_arch {
> >
> >       /* Guest Timer */
> >       struct kvm_guest_timer timer;
> > +
> > +     /* AIA Guest/VM context */
> > +     struct kvm_aia aia;
> >  };
> >
> >  struct kvm_cpu_trap {
> > @@ -220,6 +224,9 @@ struct kvm_vcpu_arch {
> >       /* SBI context */
> >       struct kvm_vcpu_sbi_context sbi_context;
> >
> > +     /* AIA VCPU context */
> > +     struct kvm_vcpu_aia aia;
>
> Maybe name this one vcpu_aia?

To be consistent with a few other variables in struct kvm_vcpu_arch, I will
add "_context" suffix to aia variable name.

>
> > +
> >       /* Cache pages needed to program page tables with spinlock held */
> >       struct kvm_mmu_memory_cache mmu_page_cache;
> >
> > diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
> > index 019df9208bdd..adbc85a94364 100644
> > --- a/arch/riscv/kvm/Makefile
> > +++ b/arch/riscv/kvm/Makefile
> > @@ -25,3 +25,4 @@ kvm-y += vcpu_sbi_base.o
> >  kvm-y += vcpu_sbi_replace.o
> >  kvm-y += vcpu_sbi_hsm.o
> >  kvm-y += vcpu_timer.o
> > +kvm-y += aia.o
>
> Shouldn't the compilation of aia.c depend on the same config(s) as the
> rest of the kernel's AIA support?

The AIA CSRs are just like other ISA extensions which we detect
from the host ISA string. A kconfig option is not required for
AIA CSRs since users can always disable AIA CSRs from
their ISA strings in DT.

>
> > diff --git a/arch/riscv/kvm/aia.c b/arch/riscv/kvm/aia.c
> > new file mode 100644
> > index 000000000000..e7fa4e014d08
> > --- /dev/null
> > +++ b/arch/riscv/kvm/aia.c
> > @@ -0,0 +1,66 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > + * Copyright (C) 2022 Ventana Micro Systems Inc.
> > + *
> > + * Authors:
> > + *   Anup Patel <apatel@ventanamicro.com>
> > + */
> > +
> > +#include <linux/kvm_host.h>
> > +#include <asm/hwcap.h>
> > +
> > +DEFINE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
> > +
> > +static inline void aia_set_hvictl(bool ext_irq_pending)
>
> I'd drop the 'inline' from functions in .c files and let the compiler
> fully decide.

Okay, I will update.

>
> > +{
> > +     unsigned long hvictl;
> > +
> > +     /*
> > +      * HVICTL.IID == 9 and HVICTL.IPRIO == 0 represents
> > +      * no interrupt in HVICTL.
> > +      */
> > +
> > +     hvictl = (IRQ_S_EXT << HVICTL_IID_SHIFT) & HVICTL_IID;
> > +     hvictl |= (ext_irq_pending) ? 1 : 0;
>
> ext_irq_pending is bool, so this can just be 'hvictl |= ext_irq_pending'.

Okay, I will update.

>
> > +     csr_write(CSR_HVICTL, hvictl);
> > +}
> > +
> > +void kvm_riscv_aia_enable(void)
> > +{
> > +     if (!kvm_riscv_aia_available())
> > +             return;
> > +
> > +     aia_set_hvictl(false);
> > +     csr_write(CSR_HVIPRIO1, 0x0);
> > +     csr_write(CSR_HVIPRIO2, 0x0);
> > +#ifdef CONFIG_32BIT
> > +     csr_write(CSR_HVIPH, 0x0);
> > +     csr_write(CSR_HIDELEGH, 0x0);
> > +     csr_write(CSR_HVIPRIO1H, 0x0);
> > +     csr_write(CSR_HVIPRIO2H, 0x0);
> > +#endif
> > +}
> > +
> > +void kvm_riscv_aia_disable(void)
> > +{
> > +     if (!kvm_riscv_aia_available())
> > +             return;
> > +
> > +     aia_set_hvictl(false);
> > +}
> > +
> > +int kvm_riscv_aia_init(void)
> > +{
> > +     if (!riscv_isa_extension_available(NULL, SxAIA))
> > +             return -ENODEV;
> > +
> > +     /* Enable KVM AIA support */
> > +     static_branch_enable(&kvm_riscv_aia_available);
> > +
> > +     return 0;
> > +}
> > +
> > +void kvm_riscv_aia_exit(void)
> > +{
> > +}
> > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> > index 58c5489d3031..d8ff44eb04ca 100644
> > --- a/arch/riscv/kvm/main.c
> > +++ b/arch/riscv/kvm/main.c
> > @@ -53,11 +53,15 @@ int kvm_arch_hardware_enable(void)
> >
> >       csr_write(CSR_HVIP, 0);
> >
> > +     kvm_riscv_aia_enable();
> > +
> >       return 0;
> >  }
> >
> >  void kvm_arch_hardware_disable(void)
> >  {
> > +     kvm_riscv_aia_disable();
> > +
> >       /*
> >        * After clearing the hideleg CSR, the host kernel will receive
> >        * spurious interrupts if hvip CSR has pending interrupts and the
> > @@ -72,6 +76,7 @@ void kvm_arch_hardware_disable(void)
> >
> >  int kvm_arch_init(void *opaque)
> >  {
> > +     int rc;
> >       const char *str;
> >
> >       if (!riscv_isa_extension_available(NULL, h)) {
> > @@ -93,6 +98,10 @@ int kvm_arch_init(void *opaque)
> >
> >       kvm_riscv_gstage_vmid_detect();
> >
> > +     rc = kvm_riscv_aia_init();
> > +     if (rc && rc != -ENODEV)
> > +             return rc;
> > +
> >       kvm_info("hypervisor extension available\n");
> >
> >       switch (kvm_riscv_gstage_mode()) {
> > @@ -115,11 +124,15 @@ int kvm_arch_init(void *opaque)
> >
> >       kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
> >
> > +     if (kvm_riscv_aia_available())
> > +             kvm_info("AIA available\n");
> > +
> >       return 0;
> >  }
> >
> >  void kvm_arch_exit(void)
> >  {
> > +     kvm_riscv_aia_exit();
> >  }
> >
> >  static int __init riscv_kvm_init(void)
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 2260adaf2de8..3cf50eadc8ce 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -135,6 +135,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
> >
> >       kvm_riscv_vcpu_timer_reset(vcpu);
> >
> > +     kvm_riscv_vcpu_aia_reset(vcpu);
> > +
> >       WRITE_ONCE(vcpu->arch.irqs_pending, 0);
> >       WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
> >
> > @@ -155,6 +157,7 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
> >
> >  int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >  {
> > +     int rc;
> >       struct kvm_cpu_context *cntx;
> >       struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
> >       unsigned long host_isa, i;
> > @@ -194,6 +197,11 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >       /* Setup VCPU timer */
> >       kvm_riscv_vcpu_timer_init(vcpu);
> >
> > +     /* Setup VCPU AIA */
> > +     rc = kvm_riscv_vcpu_aia_init(vcpu);
> > +     if (rc)
> > +             return rc;
> > +
> >       /* Reset VCPU */
> >       kvm_riscv_reset_vcpu(vcpu);
> >
> > @@ -213,6 +221,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> >
> >  void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> >  {
> > +     /* Cleanup VCPU AIA context */
> > +     kvm_riscv_vcpu_aia_deinit(vcpu);
> > +
> >       /* Cleanup VCPU timer */
> >       kvm_riscv_vcpu_timer_deinit(vcpu);
> >
> > @@ -730,6 +741,9 @@ void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu)
> >               csr->hvip &= ~mask;
> >               csr->hvip |= val;
> >       }
> > +
> > +     /* Flush AIA high interrupts */
> > +     kvm_riscv_vcpu_aia_flush_interrupts(vcpu);
> >  }
> >
> >  void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
> > @@ -755,6 +769,9 @@ void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
> >               }
> >       }
> >
> > +     /* Sync-up AIA high interrupts */
> > +     kvm_riscv_vcpu_aia_sync_interrupts(vcpu);
> > +
> >       /* Sync-up timer CSRs */
> >       kvm_riscv_vcpu_timer_sync(vcpu);
> >  }
> > @@ -791,10 +808,15 @@ int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq)
> >
> >  bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask)
> >  {
> > -     unsigned long ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK)
> > -                         << VSIP_TO_HVIP_SHIFT) & mask;
> > +     unsigned long ie;
> > +
> > +     ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK)
> > +             << VSIP_TO_HVIP_SHIFT) & mask;
> > +     if (READ_ONCE(vcpu->arch.irqs_pending) & ie)
> > +             return true;
> >
> > -     return (READ_ONCE(vcpu->arch.irqs_pending) & ie) ? true : false;
> > +     /* Check AIA high interrupts */
> > +     return kvm_riscv_vcpu_aia_has_interrupts(vcpu, mask);
> >  }
> >
> >  void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu)
> > @@ -890,6 +912,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> >       kvm_riscv_vcpu_guest_fp_restore(&vcpu->arch.guest_context,
> >                                       vcpu->arch.isa);
> >
> > +     kvm_riscv_vcpu_aia_load(vcpu, cpu);
> > +
> >       vcpu->cpu = cpu;
> >  }
> >
> > @@ -899,6 +923,8 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> >
> >       vcpu->cpu = -1;
> >
> > +     kvm_riscv_vcpu_aia_put(vcpu);
> > +
> >       kvm_riscv_vcpu_guest_fp_save(&vcpu->arch.guest_context,
> >                                    vcpu->arch.isa);
> >       kvm_riscv_vcpu_host_fp_restore(&vcpu->arch.host_context);
> > @@ -966,6 +992,7 @@ static void kvm_riscv_update_hvip(struct kvm_vcpu *vcpu)
> >       struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
> >
> >       csr_write(CSR_HVIP, csr->hvip);
> > +     kvm_riscv_vcpu_aia_update_hvip(vcpu);
> >  }
> >
> >  /*
> > @@ -1040,6 +1067,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> >
> >               local_irq_disable();
> >
> > +             /* Update AIA HW state before entering guest */
> > +             ret = kvm_riscv_vcpu_aia_update(vcpu);
> > +             if (ret <= 0) {
> > +                     local_irq_enable();
> > +                     continue;
> > +             }
> > +
> >               /*
> >                * Ensure we set mode to IN_GUEST_MODE after we disable
> >                * interrupts and before the final VCPU requests check.
> > diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c
> > index 0bb52761a3f7..07e8c121922b 100644
> > --- a/arch/riscv/kvm/vcpu_insn.c
> > +++ b/arch/riscv/kvm/vcpu_insn.c
> > @@ -213,7 +213,9 @@ struct csr_func {
> >                   unsigned long wr_mask);
> >  };
> >
> > -static const struct csr_func csr_funcs[] = { };
> > +static const struct csr_func csr_funcs[] = {
> > +     KVM_RISCV_VCPU_AIA_CSR_FUNCS
> > +};
> >
> >  /**
> >   * kvm_riscv_vcpu_csr_return -- Handle CSR read/write after user space
> > diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> > index 65a964d7e70d..bc03d2ddcb51 100644
> > --- a/arch/riscv/kvm/vm.c
> > +++ b/arch/riscv/kvm/vm.c
> > @@ -41,6 +41,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> >               return r;
> >       }
> >
> > +     kvm_riscv_aia_init_vm(kvm);
> > +
> >       kvm_riscv_guest_timer_init(kvm);
> >
> >       return 0;
> > @@ -49,6 +51,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> >  void kvm_arch_destroy_vm(struct kvm *kvm)
> >  {
> >       kvm_destroy_vcpus(kvm);
> > +
> > +     kvm_riscv_aia_destroy_vm(kvm);
> >  }
> >
> >  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> > --
> > 2.34.1
> >
>
> Thanks,
> drew

Thanks,
Anup