From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E9209440 for ; Thu, 30 Mar 2023 17:56:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05785C433D2; Thu, 30 Mar 2023 17:56:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680198986; bh=KfLu5goCJangGvLq7IT4uJ4Y7D299IzrAIPjai80bEk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L+nMZsshJS3JtocoGra7R7ti4jFW3DFgHqOJC4zJvSzinBmZ81La7HLWFD5J15X0x TDUERrDIj/GTRWtMe8sUSZLXUiKhkbXfwc+3g7r/u0QFP1u6QGZneNgDc/ZTNqK9kK FhRDcEK60Hc1xYLhk0NHTc7Y8cKJ/d8MW5SX47+PQxuAAVZzzv8jGZB6BFAnfwcxkM lenzIRds6msm+wRPz4MwEAig4cD79el9GNWYOYMwENZqsFTFYUFWaxM9HpcEbwTUFD 4zhwXPc6vmf/giXZ7CRwUMTZsDRkjHECDsgQSvOgiooMcCB6dSXKkfubV9h7HryZcY Zb9O1rs76mDiA== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1phwNb-004Rpa-Mr; Thu, 30 Mar 2023 18:48:07 +0100 From: Marc Zyngier To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Ricardo Koller , Simon Veith , Reiji Watanabe , Colton Lewis , Joey Gouly , dwmw2@infradead.org Subject: [PATCH v4 15/20] KVM: arm64: Document KVM_ARM_SET_CNT_OFFSETS and co Date: Thu, 30 Mar 2023 18:47:55 +0100 Message-Id: <20230330174800.2677007-16-maz@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230330174800.2677007-1-maz@kernel.org> References: <20230330174800.2677007-1-maz@kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, ricarkol@google.com, sveith@amazon.de, reijiw@google.com, coltonlewis@google.com, joey.gouly@arm.com, dwmw2@infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Add some basic documentation on the effects of KVM_ARM_SET_CNT_OFFSETS. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier --- Documentation/virt/kvm/api.rst | 38 ++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 62de0768d6aa..192adcb61add 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6029,6 +6029,44 @@ delivery must be provided via the "reg_aen" struct. The "pad" and "reserved" fields may be used for future extensions and should be set to 0s by userspace. +4.138 KVM_ARM_SET_COUNTER_OFFSET +-------------------------------- + +:Capability: KVM_CAP_COUNTER_OFFSET +:Architectures: arm64 +:Type: vm ioctl +:Parameters: struct kvm_arm_counter_offset (in) +:Returns: 0 on success, < 0 on error + +This capability indicates that userspace is able to apply a single VM-wide +offset to both the virtual and physical counters as viewed by the guest +using the KVM_ARM_SET_CNT_OFFSET ioctl and the following data structure: + +:: + + struct kvm_arm_counter_offset { + __u64 counter_offset; + __u64 reserved; + }; + +The offset describes a number of counter cycles that are subtracted from +both virtual and physical counter views (similar to the effects of the +CNTVOFF_EL2 and CNTPOFF_EL2 system registers, but only global). The offset +always applies to all vcpus (already created or created after this ioctl) +for this VM. + +It is userspace's responsibility to compute the offset based, for example, +on previous values of the guest counters. + +Any value other than 0 for the "reserved" field may result in an error +(-EINVAL) being returned. This ioctl can also return -EBUSY if any vcpu +ioctl is issued concurrently. + +Note that using this ioctl results in KVM ignoring subsequent userspace +writes to the CNTVCT_EL0 and CNTPCT_EL0 registers using the SET_ONE_REG +interface. No error will be returned, but the resulting offset will not be +applied. + 5. The kvm_run structure ======================== -- 2.34.1