From da40d85805937d6721b430dacfa2aaa44e3dcfb5 Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Mon, 27 Sep 2021 17:10:15 +0530 Subject: RISC-V: KVM: Document RISC-V specific parts of KVM API Document RISC-V specific parts of the KVM API, such as: - The interrupt numbers passed to the KVM_INTERRUPT ioctl. - The states supported by the KVM_{GET,SET}_MP_STATE ioctls. - The registers supported by the KVM_{GET,SET}_ONE_REG interface and the encoding of those register ids. - The exit reason KVM_EXIT_RISCV_SBI for SBI calls forwarded to userspace tool. CC: Jonathan Corbet CC: linux-doc@vger.kernel.org Signed-off-by: Anup Patel Acked-by: Palmer Dabbelt --- Documentation/virt/kvm/api.rst | 193 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 184 insertions(+), 9 deletions(-) (limited to 'Documentation/virt') diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index a6729c8cf063..0c0bf26426b3 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -532,7 +532,7 @@ translation mode. ------------------ :Capability: basic -:Architectures: x86, ppc, mips +:Architectures: x86, ppc, mips, riscv :Type: vcpu ioctl :Parameters: struct kvm_interrupt (in) :Returns: 0 on success, negative on failure. @@ -601,6 +601,23 @@ interrupt number dequeues the interrupt. This is an asynchronous vcpu ioctl and can be invoked from any thread. +RISC-V: +^^^^^^^ + +Queues an external interrupt to be injected into the virutal CPU. This ioctl +is overloaded with 2 different irq values: + +a) KVM_INTERRUPT_SET + + This sets external interrupt for a virtual CPU and it will receive + once it is ready. + +b) KVM_INTERRUPT_UNSET + + This clears pending external interrupt for a virtual CPU. + +This is an asynchronous vcpu ioctl and can be invoked from any thread. + 4.17 KVM_DEBUG_GUEST -------------------- @@ -1399,7 +1416,7 @@ for vm-wide capabilities. --------------------- :Capability: KVM_CAP_MP_STATE -:Architectures: x86, s390, arm, arm64 +:Architectures: x86, s390, arm, arm64, riscv :Type: vcpu ioctl :Parameters: struct kvm_mp_state (out) :Returns: 0 on success; -1 on error @@ -1416,7 +1433,8 @@ uniprocessor guests). Possible values are: ========================== =============================================== - KVM_MP_STATE_RUNNABLE the vcpu is currently running [x86,arm/arm64] + KVM_MP_STATE_RUNNABLE the vcpu is currently running + [x86,arm/arm64,riscv] KVM_MP_STATE_UNINITIALIZED the vcpu is an application processor (AP) which has not yet received an INIT signal [x86] KVM_MP_STATE_INIT_RECEIVED the vcpu has received an INIT signal, and is @@ -1425,7 +1443,7 @@ Possible values are: is waiting for an interrupt [x86] KVM_MP_STATE_SIPI_RECEIVED the vcpu has just received a SIPI (vector accessible via KVM_GET_VCPU_EVENTS) [x86] - KVM_MP_STATE_STOPPED the vcpu is stopped [s390,arm/arm64] + KVM_MP_STATE_STOPPED the vcpu is stopped [s390,arm/arm64,riscv] KVM_MP_STATE_CHECK_STOP the vcpu is in a special error state [s390] KVM_MP_STATE_OPERATING the vcpu is operating (running or halted) [s390] @@ -1437,8 +1455,8 @@ On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an in-kernel irqchip, the multiprocessing state must be maintained by userspace on these architectures. -For arm/arm64: -^^^^^^^^^^^^^^ +For arm/arm64/riscv: +^^^^^^^^^^^^^^^^^^^^ The only states that are valid are KVM_MP_STATE_STOPPED and KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not. @@ -1447,7 +1465,7 @@ KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not. --------------------- :Capability: KVM_CAP_MP_STATE -:Architectures: x86, s390, arm, arm64 +:Architectures: x86, s390, arm, arm64, riscv :Type: vcpu ioctl :Parameters: struct kvm_mp_state (in) :Returns: 0 on success; -1 on error @@ -1459,8 +1477,8 @@ On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an in-kernel irqchip, the multiprocessing state must be maintained by userspace on these architectures. -For arm/arm64: -^^^^^^^^^^^^^^ +For arm/arm64/riscv: +^^^^^^^^^^^^^^^^^^^^ The only states that are valid are KVM_MP_STATE_STOPPED and KVM_MP_STATE_RUNNABLE which reflect if the vcpu should be paused or not. @@ -2577,6 +2595,144 @@ following id bit patterns:: 0x7020 0000 0003 02 <0:3> +RISC-V registers are mapped using the lower 32 bits. The upper 8 bits of +that is the register group type. + +RISC-V config registers are meant for configuring a Guest VCPU and it has +the following id bit patterns:: + + 0x8020 0000 01 (32bit Host) + 0x8030 0000 01 (64bit Host) + +Following are the RISC-V config registers: + +======================= ========= ============================================= + Encoding Register Description +======================= ========= ============================================= + 0x80x0 0000 0100 0000 isa ISA feature bitmap of Guest VCPU +======================= ========= ============================================= + +The isa config register can be read anytime but can only be written before +a Guest VCPU runs. It will have ISA feature bits matching underlying host +set by default. + +RISC-V core registers represent the general excution state of a Guest VCPU +and it has the following id bit patterns:: + + 0x8020 0000 02 (32bit Host) + 0x8030 0000 02 (64bit Host) + +Following are the RISC-V core registers: + +======================= ========= ============================================= + Encoding Register Description +======================= ========= ============================================= + 0x80x0 0000 0200 0000 regs.pc Program counter + 0x80x0 0000 0200 0001 regs.ra Return address + 0x80x0 0000 0200 0002 regs.sp Stack pointer + 0x80x0 0000 0200 0003 regs.gp Global pointer + 0x80x0 0000 0200 0004 regs.tp Task pointer + 0x80x0 0000 0200 0005 regs.t0 Caller saved register 0 + 0x80x0 0000 0200 0006 regs.t1 Caller saved register 1 + 0x80x0 0000 0200 0007 regs.t2 Caller saved register 2 + 0x80x0 0000 0200 0008 regs.s0 Callee saved register 0 + 0x80x0 0000 0200 0009 regs.s1 Callee saved register 1 + 0x80x0 0000 0200 000a regs.a0 Function argument (or return value) 0 + 0x80x0 0000 0200 000b regs.a1 Function argument (or return value) 1 + 0x80x0 0000 0200 000c regs.a2 Function argument 2 + 0x80x0 0000 0200 000d regs.a3 Function argument 3 + 0x80x0 0000 0200 000e regs.a4 Function argument 4 + 0x80x0 0000 0200 000f regs.a5 Function argument 5 + 0x80x0 0000 0200 0010 regs.a6 Function argument 6 + 0x80x0 0000 0200 0011 regs.a7 Function argument 7 + 0x80x0 0000 0200 0012 regs.s2 Callee saved register 2 + 0x80x0 0000 0200 0013 regs.s3 Callee saved register 3 + 0x80x0 0000 0200 0014 regs.s4 Callee saved register 4 + 0x80x0 0000 0200 0015 regs.s5 Callee saved register 5 + 0x80x0 0000 0200 0016 regs.s6 Callee saved register 6 + 0x80x0 0000 0200 0017 regs.s7 Callee saved register 7 + 0x80x0 0000 0200 0018 regs.s8 Callee saved register 8 + 0x80x0 0000 0200 0019 regs.s9 Callee saved register 9 + 0x80x0 0000 0200 001a regs.s10 Callee saved register 10 + 0x80x0 0000 0200 001b regs.s11 Callee saved register 11 + 0x80x0 0000 0200 001c regs.t3 Caller saved register 3 + 0x80x0 0000 0200 001d regs.t4 Caller saved register 4 + 0x80x0 0000 0200 001e regs.t5 Caller saved register 5 + 0x80x0 0000 0200 001f regs.t6 Caller saved register 6 + 0x80x0 0000 0200 0020 mode Privilege mode (1 = S-mode or 0 = U-mode) +======================= ========= ============================================= + +RISC-V csr registers represent the supervisor mode control/status registers +of a Guest VCPU and it has the following id bit patterns:: + + 0x8020 0000 03 (32bit Host) + 0x8030 0000 03 (64bit Host) + +Following are the RISC-V csr registers: + +======================= ========= ============================================= + Encoding Register Description +======================= ========= ============================================= + 0x80x0 0000 0300 0000 sstatus Supervisor status + 0x80x0 0000 0300 0001 sie Supervisor interrupt enable + 0x80x0 0000 0300 0002 stvec Supervisor trap vector base + 0x80x0 0000 0300 0003 sscratch Supervisor scratch register + 0x80x0 0000 0300 0004 sepc Supervisor exception program counter + 0x80x0 0000 0300 0005 scause Supervisor trap cause + 0x80x0 0000 0300 0006 stval Supervisor bad address or instruction + 0x80x0 0000 0300 0007 sip Supervisor interrupt pending + 0x80x0 0000 0300 0008 satp Supervisor address translation and protection +======================= ========= ============================================= + +RISC-V timer registers represent the timer state of a Guest VCPU and it has +the following id bit patterns:: + + 0x8030 0000 04 + +Following are the RISC-V timer registers: + +======================= ========= ============================================= + Encoding Register Description +======================= ========= ============================================= + 0x8030 0000 0400 0000 frequency Time base frequency (read-only) + 0x8030 0000 0400 0001 time Time value visible to Guest + 0x8030 0000 0400 0002 compare Time compare programmed by Guest + 0x8030 0000 0400 0003 state Time compare state (1 = ON or 0 = OFF) +======================= ========= ============================================= + +RISC-V F-extension registers represent the single precision floating point +state of a Guest VCPU and it has the following id bit patterns:: + + 0x8020 0000 05 + +Following are the RISC-V F-extension registers: + +======================= ========= ============================================= + Encoding Register Description +======================= ========= ============================================= + 0x8020 0000 0500 0000 f[0] Floating point register 0 + ... + 0x8020 0000 0500 001f f[31] Floating point register 31 + 0x8020 0000 0500 0020 fcsr Floating point control and status register +======================= ========= ============================================= + +RISC-V D-extension registers represent the double precision floating point +state of a Guest VCPU and it has the following id bit patterns:: + + 0x8020 0000 06 (fcsr) + 0x8030 0000 06 (non-fcsr) + +Following are the RISC-V D-extension registers: + +======================= ========= ============================================= + Encoding Register Description +======================= ========= ============================================= + 0x8030 0000 0600 0000 f[0] Floating point register 0 + ... + 0x8030 0000 0600 001f f[31] Floating point register 31 + 0x8020 0000 0600 0020 fcsr Floating point control and status register +======================= ========= ============================================= + 4.69 KVM_GET_ONE_REG -------------------- @@ -5848,6 +6004,25 @@ Valid values for 'type' are: Userspace is expected to place the hypercall result into the appropriate field before invoking KVM_RUN again. +:: + + /* KVM_EXIT_RISCV_SBI */ + struct { + unsigned long extension_id; + unsigned long function_id; + unsigned long args[6]; + unsigned long ret[2]; + } riscv_sbi; +If exit reason is KVM_EXIT_RISCV_SBI then it indicates that the VCPU has +done a SBI call which is not handled by KVM RISC-V kernel module. The details +of the SBI call are available in 'riscv_sbi' member of kvm_run structure. The +'extension_id' field of 'riscv_sbi' represents SBI extension ID whereas the +'function_id' field represents function ID of given SBI extension. The 'args' +array field of 'riscv_sbi' represents parameters for the SBI call and 'ret' +array field represents return values. The userspace should update the return +values of SBI call before resuming the VCPU. For more details on RISC-V SBI +spec refer, https://github.com/riscv/riscv-sbi-doc. + :: /* Fix the size of the union. */ -- cgit v1.2.3