From mboxrd@z Thu Jan 1 00:00:00 1970 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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id D91A0C433F5 for ; Sat, 23 Apr 2022 00:03:55 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9338E49F02; Fri, 22 Apr 2022 20:03:55 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BUEh0x2hE8Sb; Fri, 22 Apr 2022 20:03:51 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4C56049F5B; Fri, 22 Apr 2022 20:03:50 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 82E0F49EE0 for ; Fri, 22 Apr 2022 20:03:48 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id k0PLsH4OeUXT for ; Fri, 22 Apr 2022 20:03:47 -0400 (EDT) Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 7238A4B1D7 for ; Fri, 22 Apr 2022 20:03:46 -0400 (EDT) Received: by mail-pf1-f201.google.com with SMTP id v13-20020aa7850d000000b0050ad8ff561aso4696262pfn.5 for ; Fri, 22 Apr 2022 17:03:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=gJH0FnHxjhQ3OwQoOUaWxoMi94ZL2qMEOjNqSNoEV4w=; b=WavbR/MRkRUIE+WLWVZxjklwgntwe6MRTW+0iVQVLYHpKn49Qis8ugmNxaWU1rQ0GN aKcPObQi0Jz5gpk/eghNvmgEXFwNKJOH7ciUYlXC0xACaow1Dxrt2CJyDrbhp+Rdfzb8 yS9CTfbdK0jV05h8iEZ0W8Cw5ZAEBqOtmHNw2N7zfI5ztbYqzamgHfwp0Mxf+ONW/pvO i7mj3D6qTeu0iw3gKbpXEpx/14AISzdXww0c7FiQjzPCcVDDIsYWp6LV/v05G4PjOzgk n//RzxBTy76ZuzLbaPZiYDbSF6usosllqCClqcupJd37iU6EyOieA/CGRmhwuEUVvjHw T+Bg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=gJH0FnHxjhQ3OwQoOUaWxoMi94ZL2qMEOjNqSNoEV4w=; b=7RRB4if5O++6Io7PLSlLOEDTWzuMMsXe7AHwjp9XrrN/CeQW+4z+7oF9KrtNPFHCZH vz6eXOr5/VoXlRnNS5cAlf1KJNxzqeigzY6O9pqlzERHp7kpXHS9+sGdTm0gGWHVFkeY vFowY612+aOHTo6JhvUHHUj5eYmuD+IgQ+CEI/6jcjAe0d+sEO6o91L/0aw/sND91fxn JyodAiWShmELSo26Z0IOqpH8N/4bUcf85DSE5xNsletfbWhAg/nA/wR58s7D9Yeb6vxE kYa8Aup2aFgUro0TnlY106TPZeZCcyjilAL9HdeCLYjlMkOxYf8pWRjn90fjDcdhxhoQ YVeA== X-Gm-Message-State: AOAM533SfiDqVXXoXMBEdWWFTqkIS7Vq1HdAHt7G+oCzZcj+jRo5Mb2Q ZLpF0z5UApxD+LtkgOndfksJ3g6Spf9Z X-Google-Smtp-Source: ABdhPJxR/oJbIbtrIwHw/znyPaMouIhLPL/4q8hCaqsy/tUN1Y3THQGFkyZuolR/wztstK5VX25KywYFOKQD X-Received: from rananta-virt.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1bcc]) (user=rananta job=sendgmr) by 2002:a17:90a:5983:b0:1c9:ee11:76df with SMTP id l3-20020a17090a598300b001c9ee1176dfmr18972362pji.95.1650672225635; Fri, 22 Apr 2022 17:03:45 -0700 (PDT) Date: Sat, 23 Apr 2022 00:03:25 +0000 In-Reply-To: <20220423000328.2103733-1-rananta@google.com> Message-Id: <20220423000328.2103733-7-rananta@google.com> Mime-Version: 1.0 References: <20220423000328.2103733-1-rananta@google.com> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog Subject: [PATCH v6 6/9] Docs: KVM: Add doc for the bitmap firmware registers From: Raghavendra Rao Ananta To: Marc Zyngier , Andrew Jones , James Morse , Alexandru Elisei , Suzuki K Poulose Cc: kvm@vger.kernel.org, Catalin Marinas , Peter Shier , linux-kernel@vger.kernel.org, Paolo Bonzini , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Add the documentation for the bitmap firmware registers in hypercalls.rst and api.rst. This includes the details for KVM_REG_ARM_STD_BMAP, KVM_REG_ARM_STD_HYP_BMAP, and KVM_REG_ARM_VENDOR_HYP_BMAP registers. Since the document is growing to carry other hypercall related information, make necessary adjustments to present the document in a generic sense, rather than being PSCI focused. Signed-off-by: Raghavendra Rao Ananta --- Documentation/virt/kvm/api.rst | 16 ++++ Documentation/virt/kvm/arm/hypercalls.rst | 94 ++++++++++++++++++----- 2 files changed, 92 insertions(+), 18 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 85c7abc51af5..ac489191d0a9 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -2542,6 +2542,22 @@ arm64 firmware pseudo-registers have the following bit pattern:: 0x6030 0000 0014 +arm64 bitmap feature firmware pseudo-registers have the following bit pattern:: + + 0x6030 0000 0016 + +The bitmap feature firmware registers exposes the hypercall services that are +available for userspace to configure. The set bits corresponds to the services +that are available for the guests to access. By default, KVM sets all the +supported bits during VM initialization. The userspace can discover the +available services via KVM_GET_ONE_REG, and write back the bitmap corresponding +to the features that it wishes guests to see via KVM_SET_ONE_REG. + +Note: These registers are immutable once any of the vCPUs of the VM has run at +least once. A KVM_SET_ONE_REG in such a scenario will return a -EBUSY to userspace. + +(See Documentation/virt/kvm/arm/hypercalls.rst for more details.) + arm64 SVE registers have the following bit patterns:: 0x6080 0000 0015 00 Zn bits[2048*slice + 2047 : 2048*slice] diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst index d52c2e83b5b8..6327c504b2fb 100644 --- a/Documentation/virt/kvm/arm/hypercalls.rst +++ b/Documentation/virt/kvm/arm/hypercalls.rst @@ -1,32 +1,32 @@ .. SPDX-License-Identifier: GPL-2.0 -========================================= -Power State Coordination Interface (PSCI) -========================================= +======================= +ARM Hypercall Interface +======================= -KVM implements the PSCI (Power State Coordination Interface) -specification in order to provide services such as CPU on/off, reset -and power-off to the guest. +KVM handles the hypercall services as requested by the guests. New hypercall +services are regularly made available by the ARM specification or by KVM (as +vendor services) if they make sense from a virtualization point of view. -The PSCI specification is regularly updated to provide new features, -and KVM implements these updates if they make sense from a virtualization -point of view. - -This means that a guest booted on two different versions of KVM can -observe two different "firmware" revisions. This could cause issues if -a given guest is tied to a particular PSCI revision (unlikely), or if -a migration causes a different PSCI version to be exposed out of the -blue to an unsuspecting guest. +This means that a guest booted on two different versions of KVM can observe +two different "firmware" revisions. This could cause issues if a given guest +is tied to a particular version of a hypercall service, or if a migration +causes a different version to be exposed out of the blue to an unsuspecting +guest. In order to remedy this situation, KVM exposes a set of "firmware pseudo-registers" that can be manipulated using the GET/SET_ONE_REG interface. These registers can be saved/restored by userspace, and set -to a convenient value if required. +to a convenient value as required. -The following register is defined: +The following registers are defined: * KVM_REG_ARM_PSCI_VERSION: + KVM implements the PSCI (Power State Coordination Interface) + specification in order to provide services such as CPU on/off, reset + and power-off to the guest. + - Only valid if the vcpu has the KVM_ARM_VCPU_PSCI_0_2 feature set (and thus has already been initialized) - Returns the current PSCI version on GET_ONE_REG (defaulting to the @@ -74,4 +74,62 @@ The following register is defined: KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED: The workaround is always active on this vCPU or it is not needed. -.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf + +Bitmap Feature Firmware Registers +--------------------------------- + +Contrary to the above registers, the following registers exposes the hypercall +services in the form of a feature-bitmap to the userspace. This bitmap is +translated to the services that are available to the guest. There is a register +defined per service call owner and can be accessed via GET/SET_ONE_REG interface. + +By default, these registers are set with the upper limit of the features that +are supported. This way userspace can discover all the electable hypercall services +via GET_ONE_REG. The user-space can write-back the desired bitmap back via +SET_ONE_REG. The features for the registers that are untouched, probably because +userspace isn't aware of them, will be exposed as is to the guest. + +Note that KVM would't allow the userspace to configure the registers anymore once +any of the vCPUs has run at least once. Instead, it will return a -EBUSY. + +The psuedo-firmware bitmap register are as follows: + +* KVM_REG_ARM_STD_BMAP: + Controls the bitmap of the ARM Standard Secure Service Calls. + + The following bits are accepted: + + Bit-0: KVM_REG_ARM_STD_BIT_TRNG_V1_0: + The bit represents the services offered under v1.0 of ARM True Random + Number Generator (TRNG) specification, ARM DEN0098. + +* KVM_REG_ARM_STD_HYP_BMAP: + Controls the bitmap of the ARM Standard Hypervisor Service Calls. + + The following bits are accepted: + + Bit-0: KVM_REG_ARM_STD_HYP_BIT_PV_TIME: + The bit represents the Paravirtualized Time service as represented by + ARM DEN0057A. + +* KVM_REG_ARM_VENDOR_HYP_BMAP: + Controls the bitmap of the Vendor specific Hypervisor Service Calls. + + The following bits are accepted: + + Bit-0: KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT + The bit represents the ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID + function-id + + Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP: + The bit represents the Precision Time Protocol KVM service. + +Errors: + + ======= ============================================================= + -ENOENT Unknown register accessed. + -EBUSY Attempt a 'write' to the register after the VM has started. + -EINVAL Invalid bitmap written to the register. + ======= ============================================================= + +.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf \ No newline at end of file -- 2.36.0.rc2.479.g8af0fa9b8e-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm