Re: [PATCH v3 4/8] RISC-V: KVM: Initial skeletal support for AIA

Anup Patel
2023-04-04T03:23:14Z

On Tue, Apr 4, 2023 at 5:20 AM Atish Patra <atishp@atishpatra.org> wrote:
>
> On Mon, Apr 3, 2023 at 3:03 PM Anup Patel <apatel@ventanamicro.com> 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>
> > Reviewed-by: Atish Patra <atishp@rivosinc.com>
> > ---
> > arch/riscv/include/asm/hwcap.h | 6 ++
> > 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 | 22 +++++-
> > arch/riscv/kvm/vcpu.c | 40 ++++++++++-
> > arch/riscv/kvm/vcpu_insn.c | 1 +
> > arch/riscv/kvm/vm.c | 4 ++
> > 9 files changed, 252 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/hwcap.h b/arch/riscv/include/asm/hwcap.h
> > index 9c8ae4399565..8087e11a5cf8 100644
> > --- a/arch/riscv/include/asm/hwcap.h
> > +++ b/arch/riscv/include/asm/hwcap.h
> > @@ -48,6 +48,12 @@
> > #define RISCV_ISA_EXT_MAX 64
> > #define RISCV_ISA_EXT_NAME_LEN_MAX 32
> >
> > +#ifdef CONFIG_RISCV_M_MODE
> > +#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SMAIA
> > +#else
> > +#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SSAIA
> > +#endif
> > +
> > #ifndef __ASSEMBLY__
> >
> > #include <linux/jump_label.h>
> > diff --git a/arch/riscv/include/asm/kvm_aia.h b/arch/riscv/include/asm/kvm_aia.h
> > new file mode 100644
> > index 000000000000..258a835d4c32
> > --- /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)
> > +
> > +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 cc7da66ee0c0..3157cf748df1 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>
> > @@ -94,6 +95,9 @@ struct kvm_arch {
> >
> > /* Guest Timer */
> > struct kvm_guest_timer timer;
> > +
> > + /* AIA Guest/VM context */
> > + struct kvm_aia aia;
> > };
> >
> > struct kvm_cpu_trap {
> > @@ -221,6 +225,9 @@ struct kvm_vcpu_arch {
> > /* SBI context */
> > struct kvm_vcpu_sbi_context sbi_context;
> >
> > + /* AIA VCPU context */
> > + struct kvm_vcpu_aia aia_context;
> > +
> > /* 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 278e97c06e0a..8031b8912a0d 100644
> > --- a/arch/riscv/kvm/Makefile
> > +++ b/arch/riscv/kvm/Makefile
> > @@ -26,3 +26,4 @@ kvm-y += vcpu_sbi_replace.o
> > kvm-y += vcpu_sbi_hsm.o
> > kvm-y += vcpu_timer.o
> > kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o vcpu_sbi_pmu.o
> > +kvm-y += aia.o
> > diff --git a/arch/riscv/kvm/aia.c b/arch/riscv/kvm/aia.c
> > new file mode 100644
> > index 000000000000..7a633331cd3e
> > --- /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 void aia_set_hvictl(bool ext_irq_pending)
> > +{
> > + 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;
> > + 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 41ad7639a17b..6396352b4e4d 100644
> > --- a/arch/riscv/kvm/main.c
> > +++ b/arch/riscv/kvm/main.c
> > @@ -44,11 +44,15 @@ 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
> > @@ -63,6 +67,7 @@ void kvm_arch_hardware_disable(void)
> >
> > static int __init riscv_kvm_init(void)
> > {
> > + int rc;
> > const char *str;
> >
> > if (!riscv_isa_extension_available(NULL, h)) {
> > @@ -84,6 +89,10 @@ static int __init riscv_kvm_init(void)
> >
> > 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()) {
> > @@ -106,12 +115,23 @@ static int __init riscv_kvm_init(void)
> >
> > kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
> >
> > - return kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
> > + if (kvm_riscv_aia_available())
> > + kvm_info("AIA available\n");
> > +
> > + rc = kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
> > + if (rc) {
> > + kvm_riscv_aia_exit();
> > + return rc;
> > + }
> > +
> > + return 0;
> > }
> > module_init(riscv_kvm_init);
> >
> > static void __exit riscv_kvm_exit(void)
> > {
> > + kvm_riscv_aia_exit();
> > +
> > kvm_exit();
> > }
> > module_exit(riscv_kvm_exit);
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 02b49cb94561..1fd54ec15622 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -137,6 +137,8 @@ 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);
> >
> > @@ -159,6 +161,7 @@ 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;
> > @@ -201,6 +204,11 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > /* setup performance monitoring */
> > kvm_riscv_vcpu_pmu_init(vcpu);
> >
> > + /* Setup VCPU AIA */
> > + rc = kvm_riscv_vcpu_aia_init(vcpu);
> > + if (rc)
> > + return rc;
> > +
> > /* Reset VCPU */
> > kvm_riscv_reset_vcpu(vcpu);
> >
> > @@ -220,6 +228,9 @@ 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);
> >
> > @@ -741,6 +752,9 @@ 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)
> > @@ -766,6 +780,9 @@ 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);
> > }
> > @@ -802,10 +819,15 @@ 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)
> > @@ -901,6 +923,8 @@ 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;
> > }
> >
> > @@ -910,6 +934,8 @@ 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);
> > @@ -977,6 +1003,7 @@ 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);
> > }
> >
> > /*
> > @@ -1051,6 +1078,13 @@ 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;
> > + }
> > +
>
> Can we update AIA hw state with only preemption disabled ?
> For CoVE (aka AP-TEE), we need interrupts enabled to issue IPIs in
> multiple scenarios.

Okay, I will update in the next revision.

Regards,
Anup

>
> > /*
> > * 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 f689337b78ff..7a6abed41bc1 100644
> > --- a/arch/riscv/kvm/vcpu_insn.c
> > +++ b/arch/riscv/kvm/vcpu_insn.c
> > @@ -214,6 +214,7 @@ struct csr_func {
> > };
> >
> > static const struct csr_func csr_funcs[] = {
> > + KVM_RISCV_VCPU_AIA_CSR_FUNCS
> > KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS
> > };
> >
> > 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
> >
>
>
> --
> Regards,
> Atish