| Message ID | 20231012051509.738750-4-apatel@ventanamicro.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | RISC-V SBI debug console extension support | expand |
On Thu, Oct 12, 2023 at 10:45:04AM +0530, Anup Patel wrote: > Currently, all SBI extensions are enabled by default which is > problematic for SBI extensions (such as DBCN) which are forwarded > to the KVM user-space because we might have an older KVM user-space > which is not aware/ready to handle newer SBI extensions. Ideally, > the SBI extensions forwarded to the KVM user-space must be > disabled by default. > > To address above, we allow certain SBI extensions to be disabled > by default so that KVM user-space must explicitly enable such > SBI extensions to receive forwarded calls from Guest VCPU. > > Signed-off-by: Anup Patel <apatel@ventanamicro.com> > --- > arch/riscv/include/asm/kvm_vcpu_sbi.h | 4 +++ > arch/riscv/kvm/vcpu.c | 6 ++++ > arch/riscv/kvm/vcpu_sbi.c | 45 ++++++++++++++++----------- > 3 files changed, 36 insertions(+), 19 deletions(-) > > diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h > index 8d6d4dce8a5e..c02bda5559d7 100644 > --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h > +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h > @@ -35,6 +35,9 @@ struct kvm_vcpu_sbi_return { > struct kvm_vcpu_sbi_extension { > unsigned long extid_start; > unsigned long extid_end; > + > + bool default_unavail; > + > /** > * SBI extension handler. It can be defined for a given extension or group of > * extension. But it should always return linux error codes rather than SBI > @@ -59,6 +62,7 @@ int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu, > 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); > +void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu); > > #ifdef CONFIG_RISCV_SBI_V01 > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01; > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index c061a1c5fe98..e087c809073c 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -141,6 +141,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) > if (rc) > return rc; > > + /* > + * Setup SBI extensions > + * NOTE: This must be the last thing to be initialized. > + */ > + kvm_riscv_vcpu_sbi_init(vcpu); With this, we no longer defer probing to the first access (whether that's by the guest or KVM userspace). With our current small set of SBI extensions where only a single one has a probe function, then this simpler approach is good enough. We can always go back to the lazy approach later if needed. > + > /* Reset VCPU */ > kvm_riscv_reset_vcpu(vcpu); > > diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c > index 9cd97091c723..1b1cee86efda 100644 > --- a/arch/riscv/kvm/vcpu_sbi.c > +++ b/arch/riscv/kvm/vcpu_sbi.c > @@ -155,14 +155,8 @@ static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu, > if (!sext) > return -ENOENT; > > - /* > - * We can't set the extension status to available here, since it may > - * have a probe() function which needs to confirm availability first, > - * but it may be too early to call that here. We can set the status to > - * unavailable, though. > - */ > - if (!reg_val) > - scontext->ext_status[sext->ext_idx] = > + scontext->ext_status[sext->ext_idx] = (reg_val) ? > + KVM_RISCV_SBI_EXT_AVAILABLE : > KVM_RISCV_SBI_EXT_UNAVAILABLE; We're missing the change to riscv_vcpu_get_sbi_ext_single() which should also drop the comment block explaining the limits to status knowledge without initial probing (which we now do) and then just check for available, i.e. diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c index bb76c3cf633f..92c42d9aba1c 100644 --- a/arch/riscv/kvm/vcpu_sbi.c +++ b/arch/riscv/kvm/vcpu_sbi.c @@ -186,15 +186,8 @@ static int riscv_vcpu_get_sbi_ext_single(struct kvm_vcpu *vcpu, if (!sext) return -ENOENT; - /* - * If the extension status is still uninitialized, then we should probe - * to determine if it's available, but it may be too early to do that - * here. The best we can do is report that the extension has not been - * disabled, i.e. we return 1 when the extension is available and also - * when it only may be available. - */ - *reg_val = scontext->ext_status[sext->ext_idx] != - KVM_RISCV_SBI_EXT_UNAVAILABLE; + *reg_val = scontext->ext_status[sext->ext_idx] == + KVM_RISCV_SBI_EXT_AVAILABLE; return 0; } > > return 0; > @@ -337,18 +331,8 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext( > scontext->ext_status[entry->ext_idx] == > KVM_RISCV_SBI_EXT_AVAILABLE) > return ext; > - if (scontext->ext_status[entry->ext_idx] == > - KVM_RISCV_SBI_EXT_UNAVAILABLE) > - return NULL; > - if (ext->probe && !ext->probe(vcpu)) { > - scontext->ext_status[entry->ext_idx] = > - KVM_RISCV_SBI_EXT_UNAVAILABLE; > - return NULL; > - } > > - scontext->ext_status[entry->ext_idx] = > - KVM_RISCV_SBI_EXT_AVAILABLE; > - return ext; > + return NULL; > } > } > > @@ -419,3 +403,26 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run) > > return ret; > } > + > +void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu) > +{ > + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context; > + const struct kvm_riscv_sbi_extension_entry *entry; > + const struct kvm_vcpu_sbi_extension *ext; > + int i; > + > + for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) { > + entry = &sbi_ext[i]; > + ext = entry->ext_ptr; > + > + if (ext->probe && !ext->probe(vcpu)) { > + scontext->ext_status[entry->ext_idx] = > + KVM_RISCV_SBI_EXT_UNAVAILABLE; > + continue; > + } > + > + scontext->ext_status[entry->ext_idx] = ext->default_unavail ? > + KVM_RISCV_SBI_EXT_UNAVAILABLE : > + KVM_RISCV_SBI_EXT_AVAILABLE; > + } > +} > -- > 2.34.1 > Thanks, drew
On Thu, Oct 19, 2023 at 1:27 PM Andrew Jones <ajones@ventanamicro.com> wrote: > > On Thu, Oct 12, 2023 at 10:45:04AM +0530, Anup Patel wrote: > > Currently, all SBI extensions are enabled by default which is > > problematic for SBI extensions (such as DBCN) which are forwarded > > to the KVM user-space because we might have an older KVM user-space > > which is not aware/ready to handle newer SBI extensions. Ideally, > > the SBI extensions forwarded to the KVM user-space must be > > disabled by default. > > > > To address above, we allow certain SBI extensions to be disabled > > by default so that KVM user-space must explicitly enable such > > SBI extensions to receive forwarded calls from Guest VCPU. > > > > Signed-off-by: Anup Patel <apatel@ventanamicro.com> > > --- > > arch/riscv/include/asm/kvm_vcpu_sbi.h | 4 +++ > > arch/riscv/kvm/vcpu.c | 6 ++++ > > arch/riscv/kvm/vcpu_sbi.c | 45 ++++++++++++++++----------- > > 3 files changed, 36 insertions(+), 19 deletions(-) > > > > diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h > > index 8d6d4dce8a5e..c02bda5559d7 100644 > > --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h > > +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h > > @@ -35,6 +35,9 @@ struct kvm_vcpu_sbi_return { > > struct kvm_vcpu_sbi_extension { > > unsigned long extid_start; > > unsigned long extid_end; > > + > > + bool default_unavail; > > + > > /** > > * SBI extension handler. It can be defined for a given extension or group of > > * extension. But it should always return linux error codes rather than SBI > > @@ -59,6 +62,7 @@ int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu, > > 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); > > +void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu); > > > > #ifdef CONFIG_RISCV_SBI_V01 > > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01; > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > > index c061a1c5fe98..e087c809073c 100644 > > --- a/arch/riscv/kvm/vcpu.c > > +++ b/arch/riscv/kvm/vcpu.c > > @@ -141,6 +141,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) > > if (rc) > > return rc; > > > > + /* > > + * Setup SBI extensions > > + * NOTE: This must be the last thing to be initialized. > > + */ > > + kvm_riscv_vcpu_sbi_init(vcpu); > > With this, we no longer defer probing to the first access (whether that's > by the guest or KVM userspace). With our current small set of SBI > extensions where only a single one has a probe function, then this > simpler approach is good enough. We can always go back to the lazy > approach later if needed. I agree. We can fallback to lazy probing in the future if required. > > > + > > /* Reset VCPU */ > > kvm_riscv_reset_vcpu(vcpu); > > > > diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c > > index 9cd97091c723..1b1cee86efda 100644 > > --- a/arch/riscv/kvm/vcpu_sbi.c > > +++ b/arch/riscv/kvm/vcpu_sbi.c > > @@ -155,14 +155,8 @@ static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu, > > if (!sext) > > return -ENOENT; > > > > - /* > > - * We can't set the extension status to available here, since it may > > - * have a probe() function which needs to confirm availability first, > > - * but it may be too early to call that here. We can set the status to > > - * unavailable, though. > > - */ > > - if (!reg_val) > > - scontext->ext_status[sext->ext_idx] = > > + scontext->ext_status[sext->ext_idx] = (reg_val) ? > > + KVM_RISCV_SBI_EXT_AVAILABLE : > > KVM_RISCV_SBI_EXT_UNAVAILABLE; > > We're missing the change to riscv_vcpu_get_sbi_ext_single() which should > also drop the comment block explaining the limits to status knowledge > without initial probing (which we now do) and then just check for > available, i.e. > > diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c > index bb76c3cf633f..92c42d9aba1c 100644 > --- a/arch/riscv/kvm/vcpu_sbi.c > +++ b/arch/riscv/kvm/vcpu_sbi.c > @@ -186,15 +186,8 @@ static int riscv_vcpu_get_sbi_ext_single(struct kvm_vcpu *vcpu, > if (!sext) > return -ENOENT; > > - /* > - * If the extension status is still uninitialized, then we should probe > - * to determine if it's available, but it may be too early to do that > - * here. The best we can do is report that the extension has not been > - * disabled, i.e. we return 1 when the extension is available and also > - * when it only may be available. > - */ > - *reg_val = scontext->ext_status[sext->ext_idx] != > - KVM_RISCV_SBI_EXT_UNAVAILABLE; > + *reg_val = scontext->ext_status[sext->ext_idx] == > + KVM_RISCV_SBI_EXT_AVAILABLE; > > return 0; > } Thanks, I will include this change in the next revision. > > > > > return 0; > > @@ -337,18 +331,8 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext( > > scontext->ext_status[entry->ext_idx] == > > KVM_RISCV_SBI_EXT_AVAILABLE) > > return ext; > > - if (scontext->ext_status[entry->ext_idx] == > > - KVM_RISCV_SBI_EXT_UNAVAILABLE) > > - return NULL; > > - if (ext->probe && !ext->probe(vcpu)) { > > - scontext->ext_status[entry->ext_idx] = > > - KVM_RISCV_SBI_EXT_UNAVAILABLE; > > - return NULL; > > - } > > > > - scontext->ext_status[entry->ext_idx] = > > - KVM_RISCV_SBI_EXT_AVAILABLE; > > - return ext; > > + return NULL; > > } > > } > > > > @@ -419,3 +403,26 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run) > > > > return ret; > > } > > + > > +void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu) > > +{ > > + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context; > > + const struct kvm_riscv_sbi_extension_entry *entry; > > + const struct kvm_vcpu_sbi_extension *ext; > > + int i; > > + > > + for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) { > > + entry = &sbi_ext[i]; > > + ext = entry->ext_ptr; > > + > > + if (ext->probe && !ext->probe(vcpu)) { > > + scontext->ext_status[entry->ext_idx] = > > + KVM_RISCV_SBI_EXT_UNAVAILABLE; > > + continue; > > + } > > + > > + scontext->ext_status[entry->ext_idx] = ext->default_unavail ? > > + KVM_RISCV_SBI_EXT_UNAVAILABLE : > > + KVM_RISCV_SBI_EXT_AVAILABLE; > > + } > > +} > > -- > > 2.34.1 > > > > Thanks, > drew Regards, Anup
diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h index 8d6d4dce8a5e..c02bda5559d7 100644 --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h @@ -35,6 +35,9 @@ struct kvm_vcpu_sbi_return { struct kvm_vcpu_sbi_extension { unsigned long extid_start; unsigned long extid_end; + + bool default_unavail; + /** * SBI extension handler. It can be defined for a given extension or group of * extension. But it should always return linux error codes rather than SBI @@ -59,6 +62,7 @@ int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu, 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); +void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu); #ifdef CONFIG_RISCV_SBI_V01 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01; diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index c061a1c5fe98..e087c809073c 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -141,6 +141,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) if (rc) return rc; + /* + * Setup SBI extensions + * NOTE: This must be the last thing to be initialized. + */ + kvm_riscv_vcpu_sbi_init(vcpu); + /* Reset VCPU */ kvm_riscv_reset_vcpu(vcpu); diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c index 9cd97091c723..1b1cee86efda 100644 --- a/arch/riscv/kvm/vcpu_sbi.c +++ b/arch/riscv/kvm/vcpu_sbi.c @@ -155,14 +155,8 @@ static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu, if (!sext) return -ENOENT; - /* - * We can't set the extension status to available here, since it may - * have a probe() function which needs to confirm availability first, - * but it may be too early to call that here. We can set the status to - * unavailable, though. - */ - if (!reg_val) - scontext->ext_status[sext->ext_idx] = + scontext->ext_status[sext->ext_idx] = (reg_val) ? + KVM_RISCV_SBI_EXT_AVAILABLE : KVM_RISCV_SBI_EXT_UNAVAILABLE; return 0; @@ -337,18 +331,8 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext( scontext->ext_status[entry->ext_idx] == KVM_RISCV_SBI_EXT_AVAILABLE) return ext; - if (scontext->ext_status[entry->ext_idx] == - KVM_RISCV_SBI_EXT_UNAVAILABLE) - return NULL; - if (ext->probe && !ext->probe(vcpu)) { - scontext->ext_status[entry->ext_idx] = - KVM_RISCV_SBI_EXT_UNAVAILABLE; - return NULL; - } - scontext->ext_status[entry->ext_idx] = - KVM_RISCV_SBI_EXT_AVAILABLE; - return ext; + return NULL; } } @@ -419,3 +403,26 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run) return ret; } + +void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu) +{ + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context; + const struct kvm_riscv_sbi_extension_entry *entry; + const struct kvm_vcpu_sbi_extension *ext; + int i; + + for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) { + entry = &sbi_ext[i]; + ext = entry->ext_ptr; + + if (ext->probe && !ext->probe(vcpu)) { + scontext->ext_status[entry->ext_idx] = + KVM_RISCV_SBI_EXT_UNAVAILABLE; + continue; + } + + scontext->ext_status[entry->ext_idx] = ext->default_unavail ? + KVM_RISCV_SBI_EXT_UNAVAILABLE : + KVM_RISCV_SBI_EXT_AVAILABLE; + } +}
Currently, all SBI extensions are enabled by default which is problematic for SBI extensions (such as DBCN) which are forwarded to the KVM user-space because we might have an older KVM user-space which is not aware/ready to handle newer SBI extensions. Ideally, the SBI extensions forwarded to the KVM user-space must be disabled by default. To address above, we allow certain SBI extensions to be disabled by default so that KVM user-space must explicitly enable such SBI extensions to receive forwarded calls from Guest VCPU. Signed-off-by: Anup Patel <apatel@ventanamicro.com> --- arch/riscv/include/asm/kvm_vcpu_sbi.h | 4 +++ arch/riscv/kvm/vcpu.c | 6 ++++ arch/riscv/kvm/vcpu_sbi.c | 45 ++++++++++++++++----------- 3 files changed, 36 insertions(+), 19 deletions(-)