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[31.30.173.16]) by smtp.gmail.com with ESMTPSA id bo17-20020a0564020b3100b0051e0c0d0a8bsm4667101edb.7.2023.07.05.04.23.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Jul 2023 04:23:27 -0700 (PDT) Date: Wed, 5 Jul 2023 13:23:26 +0200 From: Andrew Jones To: Daniel Henrique Barboza Cc: kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, anup@brainfault.org, atishp@atishpatra.org Subject: Re: [PATCH] RISC-V: KVM: provide UAPI for host SATP mode Message-ID: <20230705-8af7caeededf1b02f0a08d64@orel> References: <20230705091535.237765-1-dbarboza@ventanamicro.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230705091535.237765-1-dbarboza@ventanamicro.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230705_042331_476841_7E2AB153 X-CRM114-Status: GOOD ( 23.73 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Jul 05, 2023 at 06:15:35AM -0300, Daniel Henrique Barboza wrote: > KVM userspaces need to be aware of the host SATP to allow them to > advertise it back to the guest OS. > > Since this information is used to build the guest FDT we can't wait for > the SATP reg to be readable. We just need to read the SATP mode, thus > we can use the existing 'satp_mode' global that represents the SATP reg > with MODE set and both ASID and PPN cleared. E.g. for a 32 bit host > running with sv32 satp_mode is 0x80000000, for a 64 bit host running > sv57 satp_mode is 0xa000000000000000, and so on. > > Add a new userspace virtual config register 'satp_mode' to allow > userspace to read the current SATP mode the host is using with > GET_ONE_REG API before spinning the vcpu. > > 'satp_mode' can't be changed via KVM, so SET_ONE_REG is allowed as long > as userspace writes the existing 'satp_mode'. > > Signed-off-by: Daniel Henrique Barboza > --- > arch/riscv/include/asm/csr.h | 2 ++ > arch/riscv/include/uapi/asm/kvm.h | 1 + > arch/riscv/kvm/vcpu.c | 7 +++++++ > 3 files changed, 10 insertions(+) > > diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h > index b6acb7ed115f..be6e5c305e5b 100644 > --- a/arch/riscv/include/asm/csr.h > +++ b/arch/riscv/include/asm/csr.h > @@ -46,6 +46,7 @@ > #ifndef CONFIG_64BIT > #define SATP_PPN _AC(0x003FFFFF, UL) > #define SATP_MODE_32 _AC(0x80000000, UL) > +#define SATP_MODE_SHIFT 31 > #define SATP_ASID_BITS 9 > #define SATP_ASID_SHIFT 22 > #define SATP_ASID_MASK _AC(0x1FF, UL) > @@ -54,6 +55,7 @@ > #define SATP_MODE_39 _AC(0x8000000000000000, UL) > #define SATP_MODE_48 _AC(0x9000000000000000, UL) > #define SATP_MODE_57 _AC(0xa000000000000000, UL) > +#define SATP_MODE_SHIFT 60 > #define SATP_ASID_BITS 16 > #define SATP_ASID_SHIFT 44 > #define SATP_ASID_MASK _AC(0xFFFF, UL) > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h > index f92790c9481a..0493c078e64e 100644 > --- a/arch/riscv/include/uapi/asm/kvm.h > +++ b/arch/riscv/include/uapi/asm/kvm.h > @@ -54,6 +54,7 @@ struct kvm_riscv_config { > unsigned long marchid; > unsigned long mimpid; > unsigned long zicboz_block_size; > + unsigned long satp_mode; > }; > > /* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */ > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index 8bd9f2a8a0b9..b31acf923802 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -313,6 +313,9 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu, > case KVM_REG_RISCV_CONFIG_REG(mimpid): > reg_val = vcpu->arch.mimpid; > break; > + case KVM_REG_RISCV_CONFIG_REG(satp_mode): > + reg_val = satp_mode >> SATP_MODE_SHIFT; > + break; > default: > return -EINVAL; > } > @@ -395,6 +398,10 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu, > else > return -EBUSY; > break; > + case KVM_REG_RISCV_CONFIG_REG(satp_mode): > + if (reg_val != (satp_mode >> SATP_MODE_SHIFT)) > + return -EINVAL; > + break; > default: > return -EINVAL; > } > -- > 2.41.0 > Reviewed-by: Andrew Jones _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv