From 56d8a385b60556019ecb45d6098830c9ef6a13e0 Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Wed, 11 Oct 2023 17:52:26 +0530 Subject: RISC-V: KVM: Allow some SBI extensions to be disabled by default 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 Reviewed-by: Andrew Jones Signed-off-by: Anup Patel --- arch/riscv/kvm/vcpu.c | 6 +++++ arch/riscv/kvm/vcpu_sbi.c | 57 +++++++++++++++++++++++------------------------ 2 files changed, 34 insertions(+), 29 deletions(-) (limited to 'arch/riscv/kvm') 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..bda8b0b33343 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; @@ -188,16 +182,8 @@ 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; } @@ -337,18 +323,8 @@ 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 +395,26 @@ ecall_done: 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; + } +} -- cgit v1.2.3-58-ga151