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Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by casper.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1g5t0v-0005oE-7q for linux-arm-kernel@lists.infradead.org; Fri, 28 Sep 2018 13:41:03 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F36BF15B2; Fri, 28 Sep 2018 06:41:00 -0700 (PDT) Received: from e103592.Emea.Arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4789D3F5B7; Fri, 28 Sep 2018 06:40:59 -0700 (PDT) From: Dave Martin To: kvmarm@lists.cs.columbia.edu Subject: [RFC PATCH v2 23/23] KVM: arm64/sve: Document KVM API extensions for SVE Date: Fri, 28 Sep 2018 14:39:27 +0100 Message-Id: <1538141967-15375-24-git-send-email-Dave.Martin@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1538141967-15375-1-git-send-email-Dave.Martin@arm.com> References: <1538141967-15375-1-git-send-email-Dave.Martin@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180928_144101_560116_FF95BFA3 X-CRM114-Status: GOOD ( 25.23 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Okamoto Takayuki , Christoffer Dall , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Will Deacon , =?utf-8?q?Alex_Benn=C3=A9e?= , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP This patch adds sections to the KVM API documentation describing the extensions for supporting the Scalable Vector Extension (SVE) in guests. Signed-off-by: Dave Martin --- Documentation/virtual/kvm/api.txt | 142 +++++++++++++++++++++++++++++++++++++- 1 file changed, 139 insertions(+), 3 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index a58067b..b8257d4 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -2054,13 +2054,21 @@ Specifically: 0x6030 0000 0010 004c SPSR_UND 64 spsr[KVM_SPSR_UND] 0x6030 0000 0010 004e SPSR_IRQ 64 spsr[KVM_SPSR_IRQ] 0x6060 0000 0010 0050 SPSR_FIQ 64 spsr[KVM_SPSR_FIQ] - 0x6040 0000 0010 0054 V0 128 fp_regs.vregs[0] - 0x6040 0000 0010 0058 V1 128 fp_regs.vregs[1] + 0x6040 0000 0010 0054 V0 128 fp_regs.vregs[0] (*) + 0x6040 0000 0010 0058 V1 128 fp_regs.vregs[1] (*) ... - 0x6040 0000 0010 00d0 V31 128 fp_regs.vregs[31] + 0x6040 0000 0010 00d0 V31 128 fp_regs.vregs[31] (*) 0x6020 0000 0010 00d4 FPSR 32 fp_regs.fpsr 0x6020 0000 0010 00d5 FPCR 32 fp_regs.fpcr +(*) These encodings are not accepted for SVE-enabled vcpus. See + KVM_ARM_SVE_CONFIG for details of how SVE support is configured for + a vcpu. + + The equivalent register content can be accessed via bits [2047:0] of + the corresponding SVE Zn registers instead for vcpus that have SVE + enabled (see below). + arm64 CCSIDR registers are demultiplexed by CSSELR value: 0x6020 0000 0011 00 @@ -2070,6 +2078,14 @@ arm64 system registers have the following id bit patterns: arm64 firmware pseudo-registers have the following bit pattern: 0x6030 0000 0014 +arm64 SVE registers have the following bit patterns: + 0x6080 0000 0015 00 Zn bits[2048*slice + 2047 : 2048*slice] + 0x6050 0000 0015 04 Pn bits[256*slice + 255 : 256*slice] + 0x6050 0000 0015 060 FFR bits[256*slice + 255 : 256*slice] + + These registers are only accessible on SVE-enabled vcpus. See + KVM_ARM_SVE_CONFIG for details. + MIPS registers are mapped using the lower 32 bits. The upper 16 of that is the register group type: @@ -3700,6 +3716,126 @@ Returns: 0 on success, -1 on error This copies the vcpu's kvm_nested_state struct from userspace to the kernel. For the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE. +4.116 KVM_ARM_SVE_CONFIG + +Capability: KVM_CAP_ARM_SVE +Architectures: arm64 +Type: vm and vcpu ioctl +Parameters: struct kvm_sve_vls (in/out) +Returns: 0 on success +Errors: + EINVAL: Unrecognised subcommand or bad arguments + EBADFD: vcpu in wrong state for request + (KVM_ARM_SVE_CONFIG_SET, KVM_ARM_SVE_CONFIG_SET) + ENOMEM: Out of memory + EFAULT: Bad user address + +struct kvm_sve_vls { + __u16 cmd; + __u16 max_vq; + __u16 _reserved[2]; + __u64 required_vqs[8]; +}; + +General: + +cmd: This ioctl supports a few different subcommands, selected by the +value of cmd (described in detail in the following sections). + +_reserved[]: these fields may be meaningful to later kernels. For +forward compatibility, they must be zeroed before invoking this ioctl +for the first time on a given struct kvm_sve_vls object. (So, memset() +it to zero before first use, or allocate with calloc() for example.) + +max_vq, required_vqs[]: encode a set of SVE vector lengths. The set is +encoded as follows: + +If (a * 64 + b + 1) <= max_vq, then the bit represented by + + required_vqs[a] & ((__u64)1 << b) + +(where a is in the range 0..7 and b is in the range 0..63) +indicates that the vector length (a * 64 + b + 1) * 128 bits is +supported (KVM_ARM_SVE_CONFIG_QUERY, KVM_ARM_SVE_CONFIG_GET) or required +(KVM_ARM_SVE_CONFIG_SET). + +If (a * 64 + b + 1) > max_vq, then the vector length +(a * 64 + b + 1) * 128 bits is unsupported or prohibited respectively. +In other words, only the first max_vq bits in required_vqs[] are +significant; remaining bits are implicitly treated as if they were zero. + +max_vq must be in the range SVE_VQ_MIN (1) to SVE_VQ_MAX (512). + +See Documentation/arm64/sve.txt for an explanation of vector lengths and +the meaning associated with "VQ". + +Subcommands: + +/* values for cmd: */ +#define KVM_ARM_SVE_CONFIG_QUERY 0 /* query what the host can support */ +#define KVM_ARM_SVE_CONFIG_SET 1 /* enable SVE for vcpu and set VLs */ +#define KVM_ARM_SVE_CONFIG_GET 2 /* read the set of VLs for a vcpu */ + +Subcommand details: + +4.116.1 KVM_ARM_SVE_CONFIG_QUERY +Type: vm and vcpu + +Retrieve the full set of SVE vector lengths available for use by KVM +guests on this host. The result is independent of which vcpu this +command is invoked on. As a convenience, it may also be invoked on a +vm file descriptor, eliminating the need to create a vcpu first. + +4.116.2 KVM_ARM_SVE_CONFIG_SET +Type: vcpu only + +Enables SVE for the vcpu and sets the set of SVE vector lengths that +will be visible to the guest. + +This is the only way to enable SVE for a vcpu: if this command is not +invoked for a vcpu then SVE will not be available to the guest on this +vcpu. + +This subcommand is only permitted once per vcpu, before KVM_RUN has been +invoked for the vcpu for the first time. Otherwise, the command fails +with -EBADFD and the state of the vcpu is not modified. + +In typical use, the user should call KVM_ARM_SVE_CONFIG_QUERY first to +populate a struct kvm_sve_vls with the full set of vector lengths +available on the host, then set cmd = KVM_ARM_SVE_CONFIG_SET and +re-issue the KVM_ARM_SVE_CONFIG ioctl on the desired vcpu. This will +configure the best set of vector lengths available. When following this +approach, the maximum available vector length can also be restricted by +reducing the value of max_vq before invoking KVM_ARM_SVE_CONFIG_SET. + +Every requested vector length in the struct kvm_sve_vls argument must be +supported by the hardware. In addition, except for vector lengths +greater than the maximum requested vector length, every vector length +not requested must *not* be supported by the hardware. (The latter +restriction may be relaxed in the future.) If the requested set of +vector lengths is not supportable, the command fails with -EINVAL and +the state of the vcpu is not modified. + +Different vcpus of a vm may be configured with different sets of vector +lengths. Equally, some vcpus may have SVE enabled and some not. +However, such configurations are not recommended except for testing and +experimentation purposes. Architecturally compliant guest OSes will +work, but may or may not make effective use of the resulting +configuration. + +After a successful KVM_ARM_SVE_CONFIG_SET, KVM_ARM_SVE_CONFIG_GET can be +used to retrieve the configured set of vector lengths. + +4.116.3 KVM_ARM_SVE_CONFIG_GET +Type: vcpu only + +This subcommand returns the set of vector lengths enabled for the vcpu. +SVE must have been enabled and configured for this vcpu by a successful +prior KVM_ARM_SVE_CONFIG_SET call. Otherwise, -EBADFD is returned. + +The state of the vcpu is unchanged. + + 5. The kvm_run structure ------------------------