From patchwork Thu Dec 3 12:18:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yifei Jiang X-Patchwork-Id: 11948613 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7A3BC63777 for ; Thu, 3 Dec 2020 12:21:36 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7AE7D22245 for ; Thu, 3 Dec 2020 12:21:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7AE7D22245 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=XPmE2TfPhjrhg8mnxVVSFiFIYAGKjq/9+ln5nBwnc48=; b=cfF+Er7Zavn/Jby+CgbpqHUc3 gsruCBsPa/9XhqT5yslJ3ZE47tRLjA/GANs8hshBcKcRrTCWW+zubDX7gMi3xHOxIXS5U+PB4FUXz TwUrJUKILJxhKNzcRTljZvnS9OC9l8EOlUDE/qJXJjZJk+EOf+/5hTMPRSEJnh7JkBAst2J4QOjy3 09K+z50R4RgRPlpC1tYCN4yd4vzOY6FyxUOdxUy+KgxnVUWYvUS8umFWYG1ZmHKWUg4p40mFsfqaS D3IJlGFfI209pelyJcDobZH3HinaXsMpIyrUJ5di7mspLKIyvkDuEAecXPXJBTKtHxY8mN6SEufZp UJ8x8ptuQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kknc0-0001sj-1q; Thu, 03 Dec 2020 12:21:28 +0000 Received: from szxga04-in.huawei.com ([45.249.212.190]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kknbv-0001p3-Hi; Thu, 03 Dec 2020 12:21:25 +0000 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Cmw0d6T1hz15Wyd; Thu, 3 Dec 2020 20:20:49 +0800 (CST) Received: from huawei.com (10.174.186.236) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.487.0; Thu, 3 Dec 2020 20:21:07 +0800 From: Yifei Jiang To: , , , , , Subject: [PATCH RFC 2/3] RISC-V: KVM: Support dynamic time frequency from userspace Date: Thu, 3 Dec 2020 20:18:38 +0800 Message-ID: <20201203121839.308-3-jiangyifei@huawei.com> X-Mailer: git-send-email 2.26.2.windows.1 In-Reply-To: <20201203121839.308-1-jiangyifei@huawei.com> References: <20201203121839.308-1-jiangyifei@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.186.236] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201203_072124_109444_E251F52F X-CRM114-Status: GOOD ( 11.84 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: zhang.zhanghailiang@huawei.com, kvm@vger.kernel.org, yinyipeng1@huawei.com, victor.zhangxiaofeng@huawei.com, linux-kernel@vger.kernel.org, Yifei Jiang , kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, wu.wubin@huawei.com, dengkai1@huawei.com Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org This patch implements KVM_S/GET_ONE_REG of time frequency to support setting dynamic time frequency from userspace. When the time frequency specified by userspace is inconsistent with host 'riscv_timebase', it will use scale_mult and scale_shift to calculate guest scaling time. Signed-off-by: Yifei Jiang Signed-off-by: Yipeng Yin --- arch/riscv/include/asm/kvm_vcpu_timer.h | 9 ++++++ arch/riscv/kvm/vcpu_timer.c | 40 +++++++++++++++++++++---- 2 files changed, 44 insertions(+), 5 deletions(-) diff --git a/arch/riscv/include/asm/kvm_vcpu_timer.h b/arch/riscv/include/asm/kvm_vcpu_timer.h index 87e00d878999..41b5503de9e4 100644 --- a/arch/riscv/include/asm/kvm_vcpu_timer.h +++ b/arch/riscv/include/asm/kvm_vcpu_timer.h @@ -12,6 +12,10 @@ #include struct kvm_guest_timer { + u64 frequency; + bool need_scale; + u64 scale_mult; + u64 scale_shift; /* Time delta value */ u64 time_delta; }; @@ -38,4 +42,9 @@ int kvm_riscv_vcpu_timer_reset(struct kvm_vcpu *vcpu); void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu); int kvm_riscv_guest_timer_init(struct kvm *kvm); +static inline bool kvm_riscv_need_scale(struct kvm_guest_timer *gt) +{ + return gt->need_scale; +} + #endif diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c index f6b35180199a..2d203660a7e9 100644 --- a/arch/riscv/kvm/vcpu_timer.c +++ b/arch/riscv/kvm/vcpu_timer.c @@ -15,9 +15,38 @@ #include #include +#define SCALE_SHIFT_VALUE 48 +#define SCALE_TOLERANCE_HZ 1000 + +static void kvm_riscv_set_time_freq(struct kvm_guest_timer *gt, u64 freq) +{ + /* + * Guest time frequency and Host time frequency are identical + * if the error between them is limited within SCALE_TOLERANCE_HZ. + */ + u64 diff = riscv_timebase > freq ? + riscv_timebase - freq : freq - riscv_timebase; + gt->need_scale = (diff >= SCALE_TOLERANCE_HZ); + if (gt->need_scale) { + gt->scale_shift = SCALE_SHIFT_VALUE; + gt->scale_mult = mul_u64_u32_div(1ULL << gt->scale_shift, + freq, riscv_timebase); + } + gt->frequency = freq; +} + +static u64 kvm_riscv_scale_time(struct kvm_guest_timer *gt, u64 time) +{ + if (kvm_riscv_need_scale(gt)) + return mul_u64_u64_shr(time, gt->scale_mult, gt->scale_shift); + + return time; +} + static u64 kvm_riscv_current_cycles(struct kvm_guest_timer *gt) { - return get_cycles64() + gt->time_delta; + u64 host_time = get_cycles64(); + return kvm_riscv_scale_time(gt, host_time) + gt->time_delta; } static u64 kvm_riscv_delta_cycles2ns(u64 cycles, @@ -33,7 +62,7 @@ static u64 kvm_riscv_delta_cycles2ns(u64 cycles, cycles_delta = cycles - cycles_now; else cycles_delta = 0; - delta_ns = mul_u64_u64_div_u64(cycles_delta, NSEC_PER_SEC, riscv_timebase); + delta_ns = mul_u64_u64_div_u64(cycles_delta, NSEC_PER_SEC, gt->frequency); local_irq_restore(flags); return delta_ns; @@ -106,7 +135,7 @@ int kvm_riscv_vcpu_get_reg_timer(struct kvm_vcpu *vcpu, switch (reg_num) { case KVM_REG_RISCV_TIMER_REG(frequency): - reg_val = riscv_timebase; + reg_val = gt->frequency; break; case KVM_REG_RISCV_TIMER_REG(time): reg_val = kvm_riscv_current_cycles(gt); @@ -150,10 +179,10 @@ int kvm_riscv_vcpu_set_reg_timer(struct kvm_vcpu *vcpu, switch (reg_num) { case KVM_REG_RISCV_TIMER_REG(frequency): - ret = -EOPNOTSUPP; + kvm_riscv_set_time_freq(gt, reg_val); break; case KVM_REG_RISCV_TIMER_REG(time): - gt->time_delta = reg_val - get_cycles64(); + gt->time_delta = reg_val - kvm_riscv_scale_time(gt, get_cycles64()); break; case KVM_REG_RISCV_TIMER_REG(compare): t->next_cycles = reg_val; @@ -219,6 +248,7 @@ int kvm_riscv_guest_timer_init(struct kvm *kvm) struct kvm_guest_timer *gt = &kvm->arch.timer; gt->time_delta = -get_cycles64(); + gt->frequency = riscv_timebase; return 0; }