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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26AFBC38A2D for ; Tue, 25 Oct 2022 00:24:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230139AbiJYAXt (ORCPT ); Mon, 24 Oct 2022 20:23:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231216AbiJYAXZ (ORCPT ); Mon, 24 Oct 2022 20:23:25 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08C5210C4FF for ; Mon, 24 Oct 2022 15:47:01 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id l185-20020a6388c2000000b004610d11faddso5220473pgd.1 for ; Mon, 24 Oct 2022 15:47:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=AwCVjIH3fuXtFw6RC7AMHfdiXpbNVRxho1cvQpgLuOk=; b=MiCR/3mNpnr11BBjH3q1p/mmj/KYq1dJcrlyj302pTCZ99GrpG21yCIWInryUWsYZO NahMPSx10izNkzXzGNu6VuMqvS9PDVKRTmuekqbnd9+81WcCEoY2+sk5UfeOAQs6zAV7 fFjN2hwGqdyEbUsCyHre3QVnMTMQuZ+4CHJHlAx6bTE/u9gcMci2n1FAPJj8gdDog/3R MU/dE9tG3+BnpLNXBJFE+AzKK9U+p3SVFvYCBlqhvODCgSU7io0wxiMliLuLoCzdT+hH Es2B3h9Onr5vjws3lVIX3/Q0+dM+uxCe4S+YEfQkQkgpsz4gLAlKd0HD68TJIvdismvx kVEA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=AwCVjIH3fuXtFw6RC7AMHfdiXpbNVRxho1cvQpgLuOk=; b=PVtJxBKqDkO0pn1jlUwSy5QbKcKro4enpAIMdesQB8SgxuI+P7MY1BhX5Yd0Aj5bE1 f5L6iuOAGRz4R5JHsiRMT/4iwbWWJk3pGOY74VNKJC1vBswafkC+Es0gPtgVNncOV7UQ 6cOT1dn0IogcaVuG4cXzjdViibiAoSMOl+YwdbgueXW7fp01k5VDEOPxYV5VOc86h1y0 2i2YCVsEogqGPa98e23qlW65zoEuyp8TSrs4iO2FyenCe9vaHMU4FWwg/lpz0AIQFrTX pAFo7o4/8KFgADm6coJbxpBF/RCgjumSsQyYMDWB1fkdYAClMaVSnktkIt9nBSeta90c ZLyQ== X-Gm-Message-State: ACrzQf1ATmZK+l1eu4ge8efeLv0urBu3rlzRiGN7Ui3ufirxA/HCK5Vs mInN4kzNQyczSM4NHHcO8ckGwUQ3g6ILQyF+qXmSwzGD+MJjeMOx8ZuHVdCnTAeoL2iGF/+VFJk kAsKjqYN9ClCIdZcfgKrseBe4mlt5H9EoMufZrwNECj2nQredcQucc4xEL6yiEvR1ZCApw9cAV3 ipD1Z87lM= X-Google-Smtp-Source: AMsMyM6j/3+pJGg3lbzLNejHovD/qWs2671bNkOnwXDIiCXGYcMWROGtYQqcOfM8MiYUmnklFpfgj7HXsDciQU+IKQ== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:aa7:8011:0:b0:567:70cc:5b78 with SMTP id j17-20020aa78011000000b0056770cc5b78mr31698384pfi.29.1666651620446; Mon, 24 Oct 2022 15:47:00 -0700 (PDT) Date: Mon, 24 Oct 2022 22:46:53 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.38.0.135.g90850a2211-goog Message-ID: <20221024224657.2917482-1-dionnaglaze@google.com> Subject: [PATCH v4 0/4] Add throttling detection to sev-guest From: Dionna Glaze To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Dionna Glaze , Tom Lendacky , Paolo Bonzini , Joerg Roedel , Peter Gonda , Thomas Gleixner , Dave Hansen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The guest request synchronous API from SEV-SNP VMs to the host's security processor consumes a global resource. For this reason, AMD's docs recommend that the host implements a throttling mechanism. In order for the guest to know it's been throttled and should try its request again, we need some good-faith communication from the host that the request has been throttled. These patches work with the existing /dev/sev-guest ABI to detect a throttling code. Changes from v3: * sev-guest ratelimits itself to one request twice a second. * Fixed a type signature to use u64 instead of unsigned int * Set *exitinfo2 unconditionally after the ghcb_hv_call. Changes from v2: * Codified the non-firmware-call firmware error code as (u32)-1. * Changed sev_issue_guest_request unsigned long *fw_err argument to u64 *exitinfo2 to more accurately and type-safely describe the value that it outputs. * Changed sev_issue_guest_request to always set its exitinfo2 argument to either the non-firmware-call error code, the EXIT_INFO_2 returned from the VMM if the request failed, or 0 on success. This fixes a bug that returned uninitialized kernel stack memory to the user when there is no error. * Changed the throttle behavior to retry in the driver instead of returning -EAGAIN, due to possible message sequence number reuse on different message contents. Changes from v1: * Changed throttle error code to 2 Cc: Tom Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Peter Gonda Cc: Thomas Gleixner Cc: Dave Hansen Signed-off-by: Dionna Glaze Dionna Glaze (4): ccp: Name -1 return value as SEV_RET_NO_FW_CALL x86/sev: Change snp_guest_issue_request's fw_err virt/coco/sev-guest: Remove err in handle_guest_request virt/coco/sev-guest: interpret VMM errors from guest request arch/x86/include/asm/sev.h | 4 +- arch/x86/kernel/sev.c | 10 ++-- drivers/crypto/ccp/sev-dev.c | 2 +- drivers/virt/coco/sev-guest/sev-guest.c | 61 ++++++++++++++++++++----- include/uapi/linux/psp-sev.h | 7 +++ include/uapi/linux/sev-guest.h | 18 +++++++- 6 files changed, 82 insertions(+), 20 deletions(-) -- 2.38.0.135.g90850a2211-goog