[PATCH v5 8/8] RISC-V: KVM: Expose Zicboz to the guest

Andrew Jones
2023-02-21T20:03:07Z

Guests may use the cbo.zero instruction when the CPU has the Zicboz
extension and the hypervisor sets henvcfg.CBZE.

Add Zicboz support for KVM guests which may be enabled and
disabled from KVM userspace using the ISA extension ONE_REG API.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
---
arch/riscv/include/uapi/asm/kvm.h | 1 +
arch/riscv/kvm/vcpu.c | 4 ++++
2 files changed, 5 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index c1a1bb0fa91c..e44c1e90eaa7 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -106,6 +106,7 @@ enum KVM_RISCV_ISA_EXT_ID {
KVM_RISCV_ISA_EXT_SVINVAL,
KVM_RISCV_ISA_EXT_ZIHINTPAUSE,
KVM_RISCV_ISA_EXT_ZICBOM,
+ KVM_RISCV_ISA_EXT_ZICBOZ,
KVM_RISCV_ISA_EXT_MAX,
};

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index e5126cefbc87..198ee86cad38 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -63,6 +63,7 @@ static const unsigned long kvm_isa_ext_arr[] = {
KVM_ISA_EXT_ARR(SVPBMT),
KVM_ISA_EXT_ARR(ZIHINTPAUSE),
KVM_ISA_EXT_ARR(ZICBOM),
+ KVM_ISA_EXT_ARR(ZICBOZ),
};

static unsigned long kvm_riscv_vcpu_base2isa_ext(unsigned long base_ext)
@@ -865,6 +866,9 @@ static void kvm_riscv_vcpu_update_config(const unsigned long *isa)
if (riscv_isa_extension_available(isa, ZICBOM))
henvcfg |= (ENVCFG_CBIE | ENVCFG_CBCFE);

+ if (riscv_isa_extension_available(isa, ZICBOZ))
+ henvcfg |= ENVCFG_CBZE;
+
csr_write(CSR_HENVCFG, henvcfg);
#ifdef CONFIG_32BIT
csr_write(CSR_HENVCFGH, henvcfg >> 32);