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Message-ID: <CAAhSdy1BVyaBZ=YMbf0aTyKdvwNY8qNT6nA4KFW2nFCf9XBsPw@mail.gmail.com>
Date: Fri, 31 Mar 2023 22:58:13 +0530
From: Anup Patel <anup@...infault.org>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: Anup Patel <apatel@...tanamicro.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Atish Patra <atishp@...shpatra.org>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>, kvm@...r.kernel.org,
kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/1] RISC-V: KVM: Add ONE_REG interface to
enable/disable SBI extensions
On Fri, Mar 31, 2023 at 7:17 PM Andrew Jones <ajones@...tanamicro.com> wrote:
>
> On Fri, Mar 31, 2023 at 06:06:55PM +0530, Anup Patel wrote:
> > We add ONE_REG interface to enable/disable SBI extensions (just
> > like the ONE_REG interface for ISA extensions). This allows KVM
> > user-space to decide the set of SBI extension enabled for a Guest
> > and by default all SBI extensions are enabled.
> >
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> > arch/riscv/include/asm/kvm_vcpu_sbi.h | 8 +-
> > arch/riscv/include/uapi/asm/kvm.h | 32 ++++
> > arch/riscv/kvm/vcpu.c | 2 +
> > arch/riscv/kvm/vcpu_sbi.c | 245 ++++++++++++++++++++++++--
> > arch/riscv/kvm/vcpu_sbi_base.c | 2 +-
> > 5 files changed, 270 insertions(+), 19 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> > index 8425556af7d1..4278125a38a5 100644
> > --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> > +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> > @@ -16,6 +16,7 @@
> >
> > struct kvm_vcpu_sbi_context {
> > int return_handled;
> > + bool extension_disabled[KVM_RISCV_SBI_EXT_MAX];
>
> This could be a bitmap too, but maybe we can defer the conversion until
> later when there are more SBI extensions.
>
> > };
> >
> > struct kvm_vcpu_sbi_return {
> > @@ -45,7 +46,12 @@ void kvm_riscv_vcpu_sbi_system_reset(struct kvm_vcpu *vcpu,
> > struct kvm_run *run,
> > u32 type, u64 flags);
> > int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
> > -const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid);
> > +int kvm_riscv_vcpu_set_reg_sbi_ext(struct kvm_vcpu *vcpu,
> > + const struct kvm_one_reg *reg);
> > +int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
> > + const struct kvm_one_reg *reg);
> > +const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
> > + struct kvm_vcpu *vcpu, unsigned long extid);
> > int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
> >
> > #ifdef CONFIG_RISCV_SBI_V01
> > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> > index 92af6f3f057c..d8ead5952ed9 100644
> > --- a/arch/riscv/include/uapi/asm/kvm.h
> > +++ b/arch/riscv/include/uapi/asm/kvm.h
> > @@ -12,6 +12,7 @@
> > #ifndef __ASSEMBLY__
> >
> > #include <linux/types.h>
> > +#include <asm/bitsperlong.h>
> > #include <asm/ptrace.h>
> >
> > #define __KVM_HAVE_READONLY_MEM
> > @@ -108,6 +109,23 @@ enum KVM_RISCV_ISA_EXT_ID {
> > KVM_RISCV_ISA_EXT_MAX,
> > };
> >
> > +/*
> > + * SBI extension IDs specific to KVM. This is not the same as the SBI
> > + * extension IDs defined by the RISC-V SBI specification.
> > + */
> > +enum KVM_RISCV_SBI_EXT_ID {
> > + KVM_RISCV_SBI_EXT_V01 = 0,
> > + KVM_RISCV_SBI_EXT_TIME,
> > + KVM_RISCV_SBI_EXT_IPI,
> > + KVM_RISCV_SBI_EXT_RFENCE,
> > + KVM_RISCV_SBI_EXT_SRST,
> > + KVM_RISCV_SBI_EXT_HSM,
> > + KVM_RISCV_SBI_EXT_PMU,
> > + KVM_RISCV_SBI_EXT_EXPERIMENTAL,
> > + KVM_RISCV_SBI_EXT_VENDOR,
> > + KVM_RISCV_SBI_EXT_MAX,
> > +};
> > +
> > /* Possible states for kvm_riscv_timer */
> > #define KVM_RISCV_TIMER_STATE_OFF 0
> > #define KVM_RISCV_TIMER_STATE_ON 1
> > @@ -118,6 +136,8 @@ enum KVM_RISCV_ISA_EXT_ID {
> > /* If you need to interpret the index values, here is the key: */
> > #define KVM_REG_RISCV_TYPE_MASK 0x00000000FF000000
> > #define KVM_REG_RISCV_TYPE_SHIFT 24
> > +#define KVM_REG_RISCV_SUBTYPE_MASK 0x0000000000FF0000
> > +#define KVM_REG_RISCV_SUBTYPE_SHIFT 16
> >
> > /* Config registers are mapped as type 1 */
> > #define KVM_REG_RISCV_CONFIG (0x01 << KVM_REG_RISCV_TYPE_SHIFT)
> > @@ -152,6 +172,18 @@ enum KVM_RISCV_ISA_EXT_ID {
> > /* ISA Extension registers are mapped as type 7 */
> > #define KVM_REG_RISCV_ISA_EXT (0x07 << KVM_REG_RISCV_TYPE_SHIFT)
> >
> > +/* SBI extension registers are mapped as type 8 */
> > +#define KVM_REG_RISCV_SBI_EXT (0x08 << KVM_REG_RISCV_TYPE_SHIFT)
> > +#define KVM_REG_RISCV_SBI_SINGLE (0x0 << KVM_REG_RISCV_SUBTYPE_SHIFT)
> > +#define KVM_REG_RISCV_SBI_MULTI_EN (0x1 << KVM_REG_RISCV_SUBTYPE_SHIFT)
> > +#define KVM_REG_RISCV_SBI_MULTI_DIS (0x2 << KVM_REG_RISCV_SUBTYPE_SHIFT)
> > +#define KVM_REG_RISCV_SBI_MULTI_REG(__ext_id) \
> > + ((__ext_id) / __BITS_PER_LONG)
> > +#define KVM_REG_RISCV_SBI_MULTI_MASK(__ext_id) \
> > + (1UL << ((__ext_id) % __BITS_PER_LONG))
> > +#define KVM_REG_RISCV_SBI_MULTI_REG_LAST \
> > + KVM_REG_RISCV_SBI_MULTI_REG(KVM_RISCV_SBI_EXT_MAX - 1)
> > +
> > #endif
> >
> > #endif /* __LINUX_KVM_RISCV_H */
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 7d010b0be54e..311fd347c5a8 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -601,6 +601,8 @@ static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
> > KVM_REG_RISCV_FP_D);
> > case KVM_REG_RISCV_ISA_EXT:
> > return kvm_riscv_vcpu_set_reg_isa_ext(vcpu, reg);
> > + case KVM_REG_RISCV_SBI_EXT:
> > + return kvm_riscv_vcpu_set_reg_sbi_ext(vcpu, reg);
> > default:
> > break;
> > }
>
> Missing the kvm_riscv_vcpu_get_reg() change.
I totally missed this one. Good catch.
>
> > diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> > index 15fde15f9fb8..89e3e7bace6c 100644
> > --- a/arch/riscv/kvm/vcpu_sbi.c
> > +++ b/arch/riscv/kvm/vcpu_sbi.c
> > @@ -30,17 +30,52 @@ static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu = {
> > };
> > #endif
> >
> > -static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
> > - &vcpu_sbi_ext_v01,
> > - &vcpu_sbi_ext_base,
> > - &vcpu_sbi_ext_time,
> > - &vcpu_sbi_ext_ipi,
> > - &vcpu_sbi_ext_rfence,
> > - &vcpu_sbi_ext_srst,
> > - &vcpu_sbi_ext_hsm,
> > - &vcpu_sbi_ext_pmu,
> > - &vcpu_sbi_ext_experimental,
> > - &vcpu_sbi_ext_vendor,
> > +struct kvm_riscv_sbi_extension_entry {
> > + enum KVM_RISCV_SBI_EXT_ID dis_idx;
> > + const struct kvm_vcpu_sbi_extension *ext_ptr;
> > +};
> > +
> > +static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_V01,
> > + .ext_ptr = &vcpu_sbi_ext_v01,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_MAX, /* Can't be disabled */
> > + .ext_ptr = &vcpu_sbi_ext_base,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_TIME,
> > + .ext_ptr = &vcpu_sbi_ext_time,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_IPI,
> > + .ext_ptr = &vcpu_sbi_ext_ipi,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_RFENCE,
> > + .ext_ptr = &vcpu_sbi_ext_rfence,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_SRST,
> > + .ext_ptr = &vcpu_sbi_ext_srst,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_HSM,
> > + .ext_ptr = &vcpu_sbi_ext_hsm,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_PMU,
> > + .ext_ptr = &vcpu_sbi_ext_pmu,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
> > + .ext_ptr = &vcpu_sbi_ext_experimental,
> > + },
> > + {
> > + .dis_idx = KVM_RISCV_SBI_EXT_VENDOR,
> > + .ext_ptr = &vcpu_sbi_ext_vendor,
> > + },
> > };
> >
> > void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)
> > @@ -99,14 +134,190 @@ int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
> > return 0;
> > }
> >
> > -const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid)
> > +static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu,
> > + unsigned long reg_num,
> > + unsigned long reg_val)
> > +{
> > + unsigned long i;
> > + const struct kvm_riscv_sbi_extension_entry *sext = NULL;
> > + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
> > +
> > + if (reg_num >= KVM_RISCV_SBI_EXT_MAX ||
> > + (reg_val != 1 && reg_val != 0))
> > + return -EINVAL;
> > +
> > + for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
> > + if (sbi_ext[i].dis_idx == reg_num) {
> > + sext = &sbi_ext[i];
> > + break;
> > + }
> > + }
> > + if (!sext)
> > + return -ENOENT;
> > +
> > + scontext->extension_disabled[sext->dis_idx] = !reg_val;
> > +
> > + return 0;
> > +}
> > +
> > +static int riscv_vcpu_get_sbi_ext_single(struct kvm_vcpu *vcpu,
> > + unsigned long reg_num,
> > + unsigned long *reg_val)
> > +{
> > + unsigned long i;
> > + const struct kvm_riscv_sbi_extension_entry *sext = NULL;
> > + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
> > +
> > + if (reg_num >= KVM_RISCV_SBI_EXT_MAX)
> > + return -EINVAL;
> > +
> > + for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
> > + if (sbi_ext[i].dis_idx == reg_num) {
> > + sext = &sbi_ext[i];
> > + break;
> > + }
> > + }
> > + if (!sext)
> > + return -ENOENT;
> > +
> > + *reg_val = !scontext->extension_disabled[sext->dis_idx];
> > +
> > + return 0;
> > +}
> > +
> > +static int riscv_vcpu_set_sbi_ext_multi(struct kvm_vcpu *vcpu,
> > + unsigned long reg_num,
> > + unsigned long reg_val, bool enable)
> > +{
> > + unsigned long i, ext_id;
> > +
> > + if (reg_num > KVM_REG_RISCV_SBI_MULTI_REG_LAST)
> > + return -EINVAL;
> > +
> > + for_each_set_bit(i, ®_val, BITS_PER_LONG) {
> > + ext_id = i + reg_num * BITS_PER_LONG;
> > + if (ext_id >= KVM_RISCV_SBI_EXT_MAX)
> > + break;
> > +
> > + riscv_vcpu_set_sbi_ext_single(vcpu, ext_id, enable);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int riscv_vcpu_get_sbi_ext_multi(struct kvm_vcpu *vcpu,
> > + unsigned long reg_num,
> > + unsigned long *reg_val)
> > +{
> > + unsigned long i, ext_id, ext_val;
> > +
> > + if (reg_num > KVM_REG_RISCV_SBI_MULTI_REG_LAST)
> > + return -EINVAL;
> > +
> > + for (i = 0; i < BITS_PER_LONG; i++) {
> > + ext_id = i + reg_num * BITS_PER_LONG;
> > + if (ext_id >= KVM_RISCV_SBI_EXT_MAX)
> > + break;
> > +
> > + ext_val = 0;
> > + riscv_vcpu_get_sbi_ext_single(vcpu, ext_id, &ext_val);
> > + if (ext_val)
> > + *reg_val |= KVM_REG_RISCV_SBI_MULTI_MASK(ext_id);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +int kvm_riscv_vcpu_set_reg_sbi_ext(struct kvm_vcpu *vcpu,
> > + const struct kvm_one_reg *reg)
> > +{
> > + unsigned long __user *uaddr =
> > + (unsigned long __user *)(unsigned long)reg->addr;
> > + unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
> > + KVM_REG_SIZE_MASK |
> > + KVM_REG_RISCV_SBI_EXT);
> > + unsigned long reg_val, reg_subtype;
> > +
> > + if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
> > + return -EINVAL;
> > +
> > + if (vcpu->arch.ran_atleast_once)
> > + return -EBUSY;
> > +
> > + reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
> > + reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
> > +
> > + if (copy_from_user(®_val, uaddr, KVM_REG_SIZE(reg->id)))
> > + return -EFAULT;
> > +
> > + switch (reg_subtype) {
> > + case KVM_REG_RISCV_SBI_SINGLE:
> > + return riscv_vcpu_set_sbi_ext_single(vcpu, reg_num, reg_val);
> > + case KVM_REG_RISCV_SBI_MULTI_EN:
> > + return riscv_vcpu_set_sbi_ext_multi(vcpu, reg_num, reg_val, true);
> > + case KVM_REG_RISCV_SBI_MULTI_DIS:
> > + return riscv_vcpu_set_sbi_ext_multi(vcpu, reg_num, reg_val, false);
> > + default:
> > + return -EINVAL;
> > + };
> > +
> > + return 0;
> > +}
> > +
> > +int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
> > + const struct kvm_one_reg *reg)
> > +{
> > + int rc;
> > + unsigned long __user *uaddr =
> > + (unsigned long __user *)(unsigned long)reg->addr;
> > + unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
> > + KVM_REG_SIZE_MASK |
> > + KVM_REG_RISCV_SBI_EXT);
> > + unsigned long reg_val, reg_subtype;
> > +
> > + if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
> > + return -EINVAL;
> > +
> > + reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
> > + reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
> > +
> > + reg_val = 0;
> > + switch (reg_subtype) {
> > + case KVM_REG_RISCV_SBI_SINGLE:
> > + rc = riscv_vcpu_get_sbi_ext_single(vcpu, reg_num, ®_val);
> > + break;
> > + case KVM_REG_RISCV_SBI_MULTI_EN:
> > + case KVM_REG_RISCV_SBI_MULTI_DIS:
> > + rc = riscv_vcpu_get_sbi_ext_multi(vcpu, reg_num, ®_val);
>
> It seems odd that a user calling GET(KVM_REG_RISCV_SBI_MULTI_DIS) will get
> all the enabled extensions.
Okay, let's return bit mask of disabled extensions for
GET(KVM_REG_RISCV_SBI_MULTI_DIS).
>
> > + break;
> > + default:
> > + rc = -EINVAL;
> > + };
> > + if (rc)
> > + return rc;
> > +
> > + if (copy_to_user(uaddr, ®_val, KVM_REG_SIZE(reg->id)))
> > + return -EFAULT;
> > +
> > + return 0;
> > +}
> > +
> > +const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
> > + struct kvm_vcpu *vcpu, unsigned long extid)
> > {
> > - int i = 0;
> > + int i;
> > + const struct kvm_riscv_sbi_extension_entry *sext;
> > + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
> >
> > for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
> > - if (sbi_ext[i]->extid_start <= extid &&
> > - sbi_ext[i]->extid_end >= extid)
> > - return sbi_ext[i];
> > + sext = &sbi_ext[i];
> > + if (sext->ext_ptr->extid_start <= extid &&
> > + sext->ext_ptr->extid_end >= extid) {
> > + if (sext->dis_idx < KVM_RISCV_SBI_EXT_MAX &&
> > + scontext->extension_disabled[sext->dis_idx])
> > + return NULL;
> > + return sbi_ext[i].ext_ptr;
> > + }
> > }
> >
> > return NULL;
> > @@ -126,7 +337,7 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
> > };
> > bool ext_is_v01 = false;
> >
> > - sbi_ext = kvm_vcpu_sbi_find_ext(cp->a7);
> > + sbi_ext = kvm_vcpu_sbi_find_ext(vcpu, cp->a7);
> > if (sbi_ext && sbi_ext->handler) {
> > #ifdef CONFIG_RISCV_SBI_V01
> > if (cp->a7 >= SBI_EXT_0_1_SET_TIMER &&
> > diff --git a/arch/riscv/kvm/vcpu_sbi_base.c b/arch/riscv/kvm/vcpu_sbi_base.c
> > index 9945aff34c14..5bc570b984f4 100644
> > --- a/arch/riscv/kvm/vcpu_sbi_base.c
> > +++ b/arch/riscv/kvm/vcpu_sbi_base.c
> > @@ -44,7 +44,7 @@ static int kvm_sbi_ext_base_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> > kvm_riscv_vcpu_sbi_forward(vcpu, run);
> > retdata->uexit = true;
> > } else {
> > - sbi_ext = kvm_vcpu_sbi_find_ext(cp->a0);
> > + sbi_ext = kvm_vcpu_sbi_find_ext(vcpu, cp->a0);
> > *out_val = sbi_ext && sbi_ext->probe ?
> > sbi_ext->probe(vcpu) : !!sbi_ext;
> > }
> > --
> > 2.34.1
> >
>
> Thanks,
> drew
Regards,
Anup
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