From patchwork Wed Jun 15 10:40:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anup Patel X-Patchwork-Id: 12882106 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD279C433EF for ; Wed, 15 Jun 2022 10:41:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351994AbiFOKlO (ORCPT ); Wed, 15 Jun 2022 06:41:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351137AbiFOKlG (ORCPT ); Wed, 15 Jun 2022 06:41:06 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC41650E3D for ; Wed, 15 Jun 2022 03:41:01 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id g186so11030552pgc.1 for ; Wed, 15 Jun 2022 03:41:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ventanamicro.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=IiW6/Wj6aEziSQchLkFJstelw1x7VOvv11UX6Ci45GA=; b=hDC2YeXjiicf8IegqWbV7bw2wfUR0GwCM9pUHyUetUeDakGcQcS4hP4mDGZfuG57rn 0z6aUBG5/nEHXP1AgZF17BVhvrYb68G+RSTk1M1kMP839m8fnwQQTIe2PTia8K5zn9r0 +LYPUqZi5cwR2fyqS+2hkc6b7Up0s13OcssCT2zLOgOTb2vkQ/LGrYUI/ToC7d+HP1L/ 9xa+L4MF33pMudcOXxij6xRNAd0Dj8Ciw5Ix00Q0BAdYUdyQTetwxLnQw7rdzy5Gr4XC GU6WwN32JGNKhCzIFE7ra96OQanNptW+Ttnn9g365Wzfgv6YV+rEwN3cMCK2y4qXx3B7 gRVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=IiW6/Wj6aEziSQchLkFJstelw1x7VOvv11UX6Ci45GA=; b=IEgnnAWMNIjlmNBzff6GxW/OEr6V3QfG0VzU5z9s0cbGIXZzDzFTXrYfEAmpOSzdGi vhn7Wu7RPX+0MjjbSyXO/6SDlwh/5HqZZZF3zrlrxYq6FkfnuwIIpaiRdDKbXTyAs0Zv TCdbc6bW1/8WCXV3BfQ5HAb+F0pudNBvpoWLf9nDAzFTFHP16JWe7GjDuOZvtQwfeL1C 8CiBQXIfBcNV58V9OtG3z+dR6XUOMA2uvvXeT/ipz6CWCSaeRBv2mIzURORrG8bST4Oi tB6ZE0jHhbXb/iSx8fFhTvdkAUCra+lGFiWl+hRHgeOXeW4cHGsGtMT8N5t4lMbdS+YS rzUg== X-Gm-Message-State: AOAM5321zGqW5qpHPlP3oRnoJl7YFQhliqhLAthtNqiwb16de++LYwzO rO0fooVi7AaRCQyjbly1QHC9Fg== X-Google-Smtp-Source: ABdhPJwk/Om9g1Wzkc8oeqAMAvhlE2K0q4tary69vhdWHKGTojvtxWMYIP6Wyka2EzKjkliyjEUjbw== X-Received: by 2002:a63:8142:0:b0:3fc:c051:167f with SMTP id t63-20020a638142000000b003fcc051167fmr8428942pgd.384.1655289660932; Wed, 15 Jun 2022 03:41:00 -0700 (PDT) Received: from anup-ubuntu64-vm.. ([171.76.104.191]) by smtp.gmail.com with ESMTPSA id i19-20020a056a00225300b00522c365225csm1427273pfu.3.2022.06.15.03.40.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jun 2022 03:41:00 -0700 (PDT) From: Anup Patel To: Paolo Bonzini , Atish Patra Cc: Palmer Dabbelt , Paul Walmsley , Alistair Francis , Anup Patel , kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Anup Patel Subject: [PATCH v2 3/3] RISC-V: KVM: Add extensible CSR emulation framework Date: Wed, 15 Jun 2022 16:10:25 +0530 Message-Id: <20220615104025.941382-4-apatel@ventanamicro.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220615104025.941382-1-apatel@ventanamicro.com> References: <20220615104025.941382-1-apatel@ventanamicro.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org We add an extensible CSR emulation framework which is based upon the existing system instruction emulation. This will be useful to upcoming AIA, PMU, Nested and other virtualization features. The CSR emulation framework also has provision to emulate CSR in user space but this will be used only in very specific cases such as AIA IMSIC CSR emulation in user space or vendor specific CSR emulation in user space. By default, all CSRs not handled by KVM RISC-V will be redirected back to Guest VCPU as illegal instruction trap. Signed-off-by: Anup Patel --- arch/riscv/include/asm/kvm_host.h | 5 + arch/riscv/include/asm/kvm_vcpu_insn.h | 6 + arch/riscv/kvm/vcpu.c | 34 +++-- arch/riscv/kvm/vcpu_insn.c | 172 ++++++++++++++++++++++++- include/uapi/linux/kvm.h | 8 ++ 5 files changed, 209 insertions(+), 16 deletions(-) diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h index 03103b86dd86..a54744d7e1ba 100644 --- a/arch/riscv/include/asm/kvm_host.h +++ b/arch/riscv/include/asm/kvm_host.h @@ -64,6 +64,8 @@ struct kvm_vcpu_stat { u64 wfi_exit_stat; u64 mmio_exit_user; u64 mmio_exit_kernel; + u64 csr_exit_user; + u64 csr_exit_kernel; u64 exits; }; @@ -209,6 +211,9 @@ struct kvm_vcpu_arch { /* MMIO instruction details */ struct kvm_mmio_decode mmio_decode; + /* CSR instruction details */ + struct kvm_csr_decode csr_decode; + /* SBI context */ struct kvm_sbi_context sbi_context; diff --git a/arch/riscv/include/asm/kvm_vcpu_insn.h b/arch/riscv/include/asm/kvm_vcpu_insn.h index 3351eb61a251..350011c83581 100644 --- a/arch/riscv/include/asm/kvm_vcpu_insn.h +++ b/arch/riscv/include/asm/kvm_vcpu_insn.h @@ -18,6 +18,11 @@ struct kvm_mmio_decode { int return_handled; }; +struct kvm_csr_decode { + unsigned long insn; + int return_handled; +}; + /* Return values used by function emulating a particular instruction */ enum kvm_insn_return { KVM_INSN_EXIT_TO_USER_SPACE = 0, @@ -28,6 +33,7 @@ enum kvm_insn_return { }; void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu); +int kvm_riscv_vcpu_csr_return(struct kvm_vcpu *vcpu, struct kvm_run *run); int kvm_riscv_vcpu_virtual_insn(struct kvm_vcpu *vcpu, struct kvm_run *run, struct kvm_cpu_trap *trap); diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index 7f4ad5e4373a..21bbb9e83982 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -26,6 +26,8 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, wfi_exit_stat), STATS_DESC_COUNTER(VCPU, mmio_exit_user), STATS_DESC_COUNTER(VCPU, mmio_exit_kernel), + STATS_DESC_COUNTER(VCPU, csr_exit_user), + STATS_DESC_COUNTER(VCPU, csr_exit_kernel), STATS_DESC_COUNTER(VCPU, exits) }; @@ -851,22 +853,26 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) kvm_vcpu_srcu_read_lock(vcpu); - /* Process MMIO value returned from user-space */ - if (run->exit_reason == KVM_EXIT_MMIO) { + switch (run->exit_reason) { + case KVM_EXIT_MMIO: + /* Process MMIO value returned from user-space */ ret = kvm_riscv_vcpu_mmio_return(vcpu, vcpu->run); - if (ret) { - kvm_vcpu_srcu_read_unlock(vcpu); - return ret; - } - } - - /* Process SBI value returned from user-space */ - if (run->exit_reason == KVM_EXIT_RISCV_SBI) { + break; + case KVM_EXIT_RISCV_SBI: + /* Process SBI value returned from user-space */ ret = kvm_riscv_vcpu_sbi_return(vcpu, vcpu->run); - if (ret) { - kvm_vcpu_srcu_read_unlock(vcpu); - return ret; - } + break; + case KVM_EXIT_RISCV_CSR: + /* Process CSR value returned from user-space */ + ret = kvm_riscv_vcpu_csr_return(vcpu, vcpu->run); + break; + default: + ret = 0; + break; + } + if (ret) { + kvm_vcpu_srcu_read_unlock(vcpu); + return ret; } if (run->immediate_exit) { diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c index 75ca62a7fba5..7eb90a47b571 100644 --- a/arch/riscv/kvm/vcpu_insn.c +++ b/arch/riscv/kvm/vcpu_insn.c @@ -14,6 +14,19 @@ #define INSN_MASK_WFI 0xffffffff #define INSN_MATCH_WFI 0x10500073 +#define INSN_MATCH_CSRRW 0x1073 +#define INSN_MASK_CSRRW 0x707f +#define INSN_MATCH_CSRRS 0x2073 +#define INSN_MASK_CSRRS 0x707f +#define INSN_MATCH_CSRRC 0x3073 +#define INSN_MASK_CSRRC 0x707f +#define INSN_MATCH_CSRRWI 0x5073 +#define INSN_MASK_CSRRWI 0x707f +#define INSN_MATCH_CSRRSI 0x6073 +#define INSN_MASK_CSRRSI 0x707f +#define INSN_MATCH_CSRRCI 0x7073 +#define INSN_MASK_CSRRCI 0x707f + #define INSN_MATCH_LB 0x3 #define INSN_MASK_LB 0x707f #define INSN_MATCH_LH 0x1003 @@ -71,6 +84,7 @@ #define SH_RS1 15 #define SH_RS2 20 #define SH_RS2C 2 +#define MASK_RX 0x1f #define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1)) #define RVC_LW_IMM(x) ((RV_X(x, 6, 1) << 2) | \ @@ -104,7 +118,7 @@ #define REG_PTR(insn, pos, regs) \ ((ulong *)((ulong)(regs) + REG_OFFSET(insn, pos))) -#define GET_RM(insn) (((insn) >> 12) & 7) +#define GET_FUNCT3(insn) (((insn) >> 12) & 7) #define GET_RS1(insn, regs) (*REG_PTR(insn, SH_RS1, regs)) #define GET_RS2(insn, regs) (*REG_PTR(insn, SH_RS2, regs)) @@ -116,7 +130,6 @@ #define IMM_I(insn) ((s32)(insn) >> 20) #define IMM_S(insn) (((s32)(insn) >> 25 << 5) | \ (s32)(((insn) >> 7) & 0x1f)) -#define MASK_FUNCT3 0x7000 struct insn_func { unsigned long mask; @@ -189,7 +202,162 @@ static int wfi_insn(struct kvm_vcpu *vcpu, struct kvm_run *run, ulong insn) return KVM_INSN_CONTINUE_NEXT_SEPC; } +struct csr_func { + unsigned int base; + unsigned int count; + /* + * Possible return values are as same as "func" callback in + * "struct insn_func". + */ + int (*func)(struct kvm_vcpu *vcpu, unsigned int csr_num, + unsigned long *val, unsigned long new_val, + unsigned long wr_mask); +}; + +static const struct csr_func csr_funcs[] = { }; + +/** + * kvm_riscv_vcpu_csr_return -- Handle CSR read/write after user space + * emulation or in-kernel emulation + * + * @vcpu: The VCPU pointer + * @run: The VCPU run struct containing the CSR data + * + * Returns > 0 upon failure and 0 upon success + */ +int kvm_riscv_vcpu_csr_return(struct kvm_vcpu *vcpu, struct kvm_run *run) +{ + ulong insn; + + if (vcpu->arch.csr_decode.return_handled) + return 0; + vcpu->arch.csr_decode.return_handled = 1; + + /* Update destination register for CSR reads */ + insn = vcpu->arch.csr_decode.insn; + if ((insn >> SH_RD) & MASK_RX) + SET_RD(insn, &vcpu->arch.guest_context, + run->riscv_csr.ret_value); + + /* Move to next instruction */ + vcpu->arch.guest_context.sepc += INSN_LEN(insn); + + return 0; +} + +static int csr_insn(struct kvm_vcpu *vcpu, struct kvm_run *run, ulong insn) +{ + int i, rc = KVM_INSN_ILLEGAL_TRAP; + unsigned int csr_num = insn >> SH_RS2; + unsigned int rs1_num = (insn >> SH_RS1) & MASK_RX; + ulong rs1_val = GET_RS1(insn, &vcpu->arch.guest_context); + const struct csr_func *tcfn, *cfn = NULL; + ulong val = 0, wr_mask = 0, new_val = 0; + + /* Decode the CSR instruction */ + switch (GET_FUNCT3(insn)) { + case GET_FUNCT3(INSN_MATCH_CSRRW): + wr_mask = -1UL; + new_val = rs1_val; + break; + case GET_FUNCT3(INSN_MATCH_CSRRS): + wr_mask = rs1_val; + new_val = -1UL; + break; + case GET_FUNCT3(INSN_MATCH_CSRRC): + wr_mask = rs1_val; + new_val = 0; + break; + case GET_FUNCT3(INSN_MATCH_CSRRWI): + wr_mask = -1UL; + new_val = rs1_num; + break; + case GET_FUNCT3(INSN_MATCH_CSRRSI): + wr_mask = rs1_num; + new_val = -1UL; + break; + case GET_FUNCT3(INSN_MATCH_CSRRCI): + wr_mask = rs1_num; + new_val = 0; + break; + default: + return rc; + } + + /* Save instruction decode info */ + vcpu->arch.csr_decode.insn = insn; + vcpu->arch.csr_decode.return_handled = 0; + + /* Update CSR details in kvm_run struct */ + run->riscv_csr.csr_num = csr_num; + run->riscv_csr.new_value = new_val; + run->riscv_csr.write_mask = wr_mask; + run->riscv_csr.ret_value = 0; + + /* Find in-kernel CSR function */ + for (i = 0; i < ARRAY_SIZE(csr_funcs); i++) { + tcfn = &csr_funcs[i]; + if ((tcfn->base <= csr_num) && + (csr_num < (tcfn->base + tcfn->count))) { + cfn = tcfn; + break; + } + } + + /* First try in-kernel CSR emulation */ + if (cfn && cfn->func) { + rc = cfn->func(vcpu, csr_num, &val, new_val, wr_mask); + if (rc > KVM_INSN_EXIT_TO_USER_SPACE) { + if (rc == KVM_INSN_CONTINUE_NEXT_SEPC) { + run->riscv_csr.ret_value = val; + vcpu->stat.csr_exit_kernel++; + kvm_riscv_vcpu_csr_return(vcpu, run); + rc = KVM_INSN_CONTINUE_SAME_SEPC; + } + return rc; + } + } + + /* Exit to user-space for CSR emulation */ + if (rc <= KVM_INSN_EXIT_TO_USER_SPACE) { + vcpu->stat.csr_exit_user++; + run->exit_reason = KVM_EXIT_RISCV_CSR; + } + + return rc; +} + static const struct insn_func system_opcode_funcs[] = { + { + .mask = INSN_MASK_CSRRW, + .match = INSN_MATCH_CSRRW, + .func = csr_insn, + }, + { + .mask = INSN_MASK_CSRRS, + .match = INSN_MATCH_CSRRS, + .func = csr_insn, + }, + { + .mask = INSN_MASK_CSRRC, + .match = INSN_MATCH_CSRRC, + .func = csr_insn, + }, + { + .mask = INSN_MASK_CSRRWI, + .match = INSN_MATCH_CSRRWI, + .func = csr_insn, + }, + { + .mask = INSN_MASK_CSRRSI, + .match = INSN_MATCH_CSRRSI, + .func = csr_insn, + }, + { + .mask = INSN_MASK_CSRRCI, + .match = INSN_MATCH_CSRRCI, + .func = csr_insn, + }, { .mask = INSN_MASK_WFI, .match = INSN_MATCH_WFI, diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 5088bd9f1922..c48fd3d1c45b 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -270,6 +270,7 @@ struct kvm_xen_exit { #define KVM_EXIT_X86_BUS_LOCK 33 #define KVM_EXIT_XEN 34 #define KVM_EXIT_RISCV_SBI 35 +#define KVM_EXIT_RISCV_CSR 36 /* For KVM_EXIT_INTERNAL_ERROR */ /* Emulate instruction failed. */ @@ -496,6 +497,13 @@ struct kvm_run { unsigned long args[6]; unsigned long ret[2]; } riscv_sbi; + /* KVM_EXIT_RISCV_CSR */ + struct { + unsigned long csr_num; + unsigned long new_value; + unsigned long write_mask; + unsigned long ret_value; + } riscv_csr; /* Fix the size of the union. */ char padding[256]; };