From nobody Thu Nov 28 05:41:16 2024 Received: from smtp-fw-80007.amazon.com (smtp-fw-80007.amazon.com [99.78.197.218]) (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 9E80715B0EC; Fri, 4 Oct 2024 14:08:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=99.78.197.218 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728050919; cv=none; b=J5wG5YqdZFy50Jd/YTPOexC2FhVzzkhcZYrFQcHysMYVa19d5seuVnGYi3gZVE+2Wi3W1/gQlfn0arzVme8wwBTbmcCefbkOAAHymB7jBQC5mQtQAZmz7nhacPZRcKWYoVMQxQ0P5hupFqbhw+N5bmy7KIyHypvlZGHXAGipcNk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728050919; c=relaxed/simple; bh=uDS66yWU/o+mC6Ph2xwQoCR3wmyAWrHGhVUeB3qamNk=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=n3imtLw/la48mruEiEiTgZ4CvTAy8OtJN93BfSARILPH28PtUb83IQ24MVUU2TwI1ix435GK7C0rFeNtwjCO0YtZ8VCE6GPPWcJ4vuLqUGTVA4urJRhUl1O3m2pTFObcEjlJU1FO49qKBfZbxXClMU+KFGMd5ht+lZCpkLip8Yk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.de; spf=pass smtp.mailfrom=amazon.de; dkim=pass (1024-bit key) header.d=amazon.de header.i=@amazon.de header.b=XVyxGRyL; arc=none smtp.client-ip=99.78.197.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.de header.i=@amazon.de header.b="XVyxGRyL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1728050917; x=1759586917; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=wYFKE2E4waTHClkNCyjDT6IPnkP81VWl5E6BczCRIVg=; b=XVyxGRyL+2NzObCmDwtvkHo6CQgA+eVM1AXS2sXZMuwGWXeGDqNAbPhi 8QCAbnXbLIhTg1HWJfbudYoXGL02KfI8s+JiElMDq1DwFF0unFgEFwR4Z MNnTBzgqv13Ui7evu37Um2dBrJJUe3XGTRBOtoaTMpSovxv1JiEFrM/p7 U=; X-IronPort-AV: E=Sophos;i="6.11,177,1725321600"; d="scan'208";a="339710549" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.25.36.210]) by smtp-border-fw-80007.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2024 14:08:33 +0000 Received: from EX19MTAUWC002.ant.amazon.com [10.0.21.151:16033] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.6.41:2525] with esmtp (Farcaster) id 8a3d9a7d-a200-4716-80e4-178ca71dcd05; Fri, 4 Oct 2024 14:08:32 +0000 (UTC) X-Farcaster-Flow-ID: 8a3d9a7d-a200-4716-80e4-178ca71dcd05 Received: from EX19D020UWA004.ant.amazon.com (10.13.138.231) by EX19MTAUWC002.ant.amazon.com (10.250.64.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Fri, 4 Oct 2024 14:08:31 +0000 Received: from EX19MTAUEC002.ant.amazon.com (10.252.135.146) by EX19D020UWA004.ant.amazon.com (10.13.138.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Fri, 4 Oct 2024 14:08:31 +0000 Received: from email-imr-corp-prod-iad-all-1b-af42e9ba.us-east-1.amazon.com (10.43.8.6) by mail-relay.amazon.com (10.252.135.146) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34 via Frontend Transport; Fri, 4 Oct 2024 14:08:31 +0000 Received: from dev-dsk-nikwip-1b-bc9ec026.eu-west-1.amazon.com (dev-dsk-nikwip-1b-bc9ec026.eu-west-1.amazon.com [10.253.74.52]) by email-imr-corp-prod-iad-all-1b-af42e9ba.us-east-1.amazon.com (Postfix) with ESMTPS id C781B443FC; Fri, 4 Oct 2024 14:08:29 +0000 (UTC) From: Nikolas Wipper To: Vitaly Kuznetsov CC: Nicolas Saenz Julienne , Alexander Graf , James Gowans , , Sean Christopherson , "Paolo Bonzini" , Thomas Gleixner , "Ingo Molnar" , Borislav Petkov , Dave Hansen , Nikolas Wipper , , , , , , "Nikolas Wipper" Subject: [PATCH 1/7] KVM: Add API documentation for KVM_HYPERV_SET_TLB_FLUSH_INHIBIT Date: Fri, 4 Oct 2024 14:08:04 +0000 Message-ID: <20241004140810.34231-2-nikwip@amazon.de> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20241004140810.34231-1-nikwip@amazon.de> References: <20241004140810.34231-1-nikwip@amazon.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add API documentation for the new KVM_HYPERV_SET_TLB_FLUSH_INHIBIT ioctl. Signed-off-by: Nikolas Wipper --- Documentation/virt/kvm/api.rst | 41 ++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index a4b7dc4a9dda..9c11a8af336b 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6443,6 +6443,47 @@ the capability to be present. `flags` must currently be zero. =20 =20 +4.144 KVM_HYPERV_SET_TLB_FLUSH_INHIBIT +-------------------------------------- + +:Capability: KVM_CAP_HYPERV_TLB_FLUSH_INHIBIT +:Architectures: x86 +:Type: vcpu ioctl +:Parameters: struct kvm_hyperv_tlb_flush_inhibit +:returnReturns: 0 on success, this ioctl can't fail + +KVM_HYPERV_SET_TLB_FLUSH_INHIBIT allows userspace to prevent Hyper-V hyper= -calls +that remotely flush a vCPU's TLB, i.e. HvFlushVirtualAddressSpace(Ex)/ +HvFlushVirtualAddressList(Ex). When the flag is set, a vCPU attempting to = flush +an inhibited vCPU will be suspended and will only resume once the flag is +cleared again using this ioctl. During suspension, the vCPU will not finis= h the +hyper-call, but may enter the guest to retry it. Because it is caused by a +hyper-call, the suspension naturally happens on a guest instruction bounda= ry. +This behaviour and the suspend state itself are specified in Microsoft's +"Hypervisor Top Level Functional Specification" (TLFS). + +:: + + /* for KVM_HYPERV_SET_TLB_FLUSH_INHIBIT */ + struct kvm_hyperv_tlb_flush_inhibit { + /* in */ + __u16 flags; + #define KVM_HYPERV_UNINHIBIT_TLB_FLUSH 0 + #define KVM_HYPERV_INHIBIT_TLB_FLUSH 1 + __u8 inhibit; + __u8 padding[5]; + }; + +No flags are specified so far, the corresponding field must be set to zero, +otherwise the ioctl will fail with exit code -EINVAL. + +The suspension is transparent to userspace. It won't cause KVM_RUN to retu= rn or +the MP state to be changed. The suspension cannot be manually induced or e= xited +apart from changing the TLB flush inhibit flag of a targeted processor. + +There is no way for userspace to query the state of the flush inhibit flag. +Userspace must keep track of the required state itself. + 5. The kvm_run structure =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 --=20 2.40.1 Amazon Web Services Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597