From nobody Sun Sep 14 09:38:55 2025 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 E4DF5C61D9D for ; Tue, 24 Jan 2023 21:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234833AbjAXVPj (ORCPT ); Tue, 24 Jan 2023 16:15:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234850AbjAXVP1 (ORCPT ); Tue, 24 Jan 2023 16:15:27 -0500 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA6F4518C1 for ; Tue, 24 Jan 2023 13:15:19 -0800 (PST) Received: by mail-pl1-x649.google.com with SMTP id i16-20020a17090332d000b00194a7b146b2so9692869plr.20 for ; Tue, 24 Jan 2023 13:15:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=qdpYTJi6DrEaArTeHPrwK423y1IyzC0SEKOtBYqJqyA=; b=O1Znx44one+S9tJCsVeqZG//Oy3Z7HiLbbNBfLhe6leUWQJn3PlKWZSGEYrC3B0b3F LszMM8V42gGpWxFUZdIY3wy0EVJb5wUQtdtXd1PgO54dpOq0cg4M4r0BJ+867iywOHOe jXyLCVER6VkvmEg6OMf2scfzbp6NjBYfjSfnRK32JzFKSmqhFywFdu5kklgaLO70TU68 oOthsxyqYem+l4Ofc0Wd32iNnTKHGI3P49d+eLhYRCczKyIQ5hnoa6MdvzTBYWZucFdV xcHXJzsM8E14arwQbS711ccDB/p4ZlzywtyCbRHEDTsKYftipEmpqzrFtBrzXxPDAha1 A/FQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=qdpYTJi6DrEaArTeHPrwK423y1IyzC0SEKOtBYqJqyA=; b=QyVPKzt3i1PAnKmwBlsXj1feY59d4J5ALkfN/8MUStI7KXNsgulvUk/EC2UklgYoo/ RKETxfQAQe98wcuLG7gAXUg8XrJ06Y13U/rMdAfEoZMrf8a9/fYEpIfilWCAehkJphgJ bqupyzALZGuTN4rPih/V7fTR44jikEmh7o8oTfrbnrMq3BIl2Iem5p1FFiW3m1FZ4Orx gD39dhsCUpJi0VUHBHwaE3N9WUKJao8C7e+Ay5WcBLijkbJ6X3GTKYPfmuVTd+zDJBtE OnFAODvb/vQBcGW2evwrQWFZlQaa/Pu1xOkrs0MDbhZQivrcya9oOdKsrfL3cfVvhIeE hBDg== X-Gm-Message-State: AO0yUKUrpgVVSPAxr2o90IiWXIlFl2Q26nDlEhzca2v1yi5VrCfwboRU hcbXdYCV4VoQ2ZcdtSPd0pY1Nvggo/qxWuPnsrGkrN1pwQT8iznqNhA+75SEGZqZJrtL1OZV6pC 1pZz/YRtASDTWJ5NwQ7MX9UP6i0DV4c6C0EkZymEkLEFL4YT6Nl+LJ/2PQUKZ/Tb4deBUkHR15O T4P3DCFtc= X-Google-Smtp-Source: AK7set/UybPnVRpB/0RbOsG8/I8hrXyhSIq90L9hS3r0XIRTcNgVIlT5CvcsCFzlPEELqiNxorn9Pbggci7ho9pY3w== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a17:903:485:b0:196:10e1:bd69 with SMTP id jj5-20020a170903048500b0019610e1bd69mr616333plb.8.1674594919163; Tue, 24 Jan 2023 13:15:19 -0800 (PST) Date: Tue, 24 Jan 2023 21:14:52 +0000 In-Reply-To: <20230124211455.2563674-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20230124211455.2563674-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.39.1.405.gd4c25cc71f-goog Message-ID: <20230124211455.2563674-2-dionnaglaze@google.com> Subject: [PATCH v13 1/4] virt/coco/sev-guest: Add throttling awareness 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 , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Venu Busireddy , Michael Roth , "Kirill A. Shutemov" , Michael Sterritt Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The host is permitted and encouraged to throttle guest requests to the AMD-SP since it is a shared resource across all VMs. Without throttling-awareness, the host returning an error will immediately lock out access to the VMPCK, which makes the VM less useful as it can't attest itself. Since throttling is expected to be a common occurrence, a cooperative host can return a VMM error code that the request was throttled. The driver interprets the upper 32 bits of exitinfo2 as a VMM error code. For safety, since the encryption algorithm in GHCBv2 is AES_GCM, control must remain in the kernel to complete the request with the current sequence number. Returning without finishing the request allows the the guest to make another request but with different message contents. This is IV reuse, and breaks cryptographic protections. A guest request may not make it to the AMD-SP before the host returns to the guest, so the err local variable in handle_guest_request must be initialized the same way fw_err is. snp_issue_guest_request similarly should set fw_err whether or not the value is non-zero, in order to appropriately clear the error value when zero. Cc: Tom Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Peter Gonda Cc: Thomas Gleixner Cc: Dave Hansen Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Venu Busireddy Cc: Michael Roth Cc: "Kirill A. Shutemov" Cc: Michael Sterritt Fixes: d5af44dde546 ("x86/sev: Provide support for SNP guest request NAEs") Signed-off-by: Dionna Glaze --- arch/x86/include/asm/sev-common.h | 3 ++- arch/x86/kernel/sev.c | 3 +-- drivers/virt/coco/sev-guest/sev-guest.c | 11 ++++++++++- 3 files changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-c= ommon.h index b8357d6ecd47..b63be696b776 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -128,8 +128,9 @@ struct snp_psc_desc { struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY]; } __packed; =20 -/* Guest message request error code */ +/* Guest message request error codes */ #define SNP_GUEST_REQ_INVALID_LEN BIT_ULL(32) +#define SNP_GUEST_REQ_ERR_BUSY BIT_ULL(33) =20 #define GHCB_MSR_TERM_REQ 0x100 #define GHCB_MSR_TERM_REASON_SET_POS 12 diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 679026a640ef..a908ffc2dfba 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2212,14 +2212,13 @@ int snp_issue_guest_request(u64 exit_code, struct s= np_req_data *input, unsigned if (ret) goto e_put; =20 + *fw_err =3D ghcb->save.sw_exit_info_2; if (ghcb->save.sw_exit_info_2) { /* Number of expected pages are returned in RBX */ if (exit_code =3D=3D SVM_VMGEXIT_EXT_GUEST_REQUEST && ghcb->save.sw_exit_info_2 =3D=3D SNP_GUEST_REQ_INVALID_LEN) input->data_npages =3D ghcb_get_rbx(ghcb); =20 - *fw_err =3D ghcb->save.sw_exit_info_2; - ret =3D -EIO; } =20 diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index 4ec4174e05a3..3d6551fdf06f 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -322,7 +322,7 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in u8 type, void *req_buf, size_t req_sz, void *resp_buf, u32 resp_sz, __u64 *fw_err) { - unsigned long err; + unsigned long err =3D 0xff; u64 seqno; int rc; =20 @@ -338,6 +338,7 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in if (rc) return rc; =20 +retry: /* * Call firmware to process the request. In this function the encrypted * message enters shared memory with the host. So after this call the @@ -346,6 +347,14 @@ static int handle_guest_request(struct snp_guest_dev *= snp_dev, u64 exit_code, in */ rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); =20 + /* + * The host may return SNP_GUEST_REQ_ERR_EBUSY if the request has been + * throttled. Retry in the driver to avoid returning and reusing the + * message sequence number on a different message. + */ + if (err =3D=3D SNP_GUEST_REQ_ERR_BUSY) + goto retry; + /* * If the extended guest request fails due to having too small of a * certificate data buffer, retry the same guest request without the --=20 2.39.1.405.gd4c25cc71f-goog From nobody Sun Sep 14 09:38:55 2025 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 C04E5C54E94 for ; Tue, 24 Jan 2023 21:16:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234903AbjAXVQB (ORCPT ); Tue, 24 Jan 2023 16:16:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234882AbjAXVPi (ORCPT ); Tue, 24 Jan 2023 16:15:38 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F1EA4903A for ; Tue, 24 Jan 2023 13:15:23 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id a18-20020a62bd12000000b0056e7b61ec78so7285973pff.17 for ; Tue, 24 Jan 2023 13:15:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=nI8g4HK84XEnirb7lePLViKdpyhNA5CP1Cst9JmMi5Y=; b=qIKw7KlhcMtg+UFKVLR/9KFMYZ9rcvDTnnOKXWbscj7BPR6fhxV2gx8g85b1FV27NK n+EGQ1CV2OY0QTHRc+cKsaR1WG13o6ygQ9l57sVS/W0ezXA/ca0m6j5jLSDmBFzayoDb jHo0b8xPwC4d5yRoJpIDDE4lK7BBDvc2T2Ru43p3K9VjR/3dl3DGHL2x6khfULc2p/Xw h9qyhUXVbBqX26FcQyxKMUTCAJdUn1V+l291NTs1vYTP5rLif+XhAc6AWYbKFbD6LgAa 49a23IVGxqJQBAVHtN+VAYfb1Bab/KqdYIxTaRVKOSBAFmziqwhTdcXloQinjZXrigDp kdmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=nI8g4HK84XEnirb7lePLViKdpyhNA5CP1Cst9JmMi5Y=; b=DpaWFEJI1APcjHxwft/eGMHa6ffq174tDmvnEGn1ZJVdj4iDTqApMffhOTqtRa+2sq bINx6ightdR1PWCZ7kFILbRXZqNmlP5PPQvFuUTpb/+xAjUFXG4LZ8aO4Lg5fDYzh4tv MH+pqMCFJgl9Gafy7nNxzCJK6M7uySkHBWbNbqI/rSB0fWw8Y8uLMiXVWUmlXvDIPwSc AUW37J7fDbiKSlw36WhU8IUjmoRGHIvxrctUSOA35ogm3jxeW96o3qIkwIFDHT9ozAm3 7+NoXdRgSKqpZICIb7vQiNQBHiKMDdS1nb1CosWnsxZ4ECccSrgThb+5FJ3rbdMQrDaX SpMQ== X-Gm-Message-State: AO0yUKVut0clIsrjFU29eztBC20vDggW4ngjF396gimhg1jY60pMt1H7 SsAL6RatJ/tLaPHftqYyoF4gHofBS7q7MU3O9Xn7k5ZEt511kNTa8Ffhm9C/KwCMsHDVCnL9h7L ZPzGs8gwku5uqVIJor39vDVhfBVR4Cg6iY4cf5n6R00MpTa/tSc5Q+qWM949KNsVi0hB7eSHDz7 bz7aAdkS8= X-Google-Smtp-Source: AK7set9hAYuLijlZZ/UKUkVmnthi6QP0tHYRF+o2x0weNdcjzHb0WPB6xHGhbNGWQ9B09ym+P7SV7kzXwuPW9JG6+g== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a17:90a:8b8d:b0:225:eaa2:3f5d with SMTP id z13-20020a17090a8b8d00b00225eaa23f5dmr55767pjn.2.1674594921092; Tue, 24 Jan 2023 13:15:21 -0800 (PST) Date: Tue, 24 Jan 2023 21:14:53 +0000 In-Reply-To: <20230124211455.2563674-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20230124211455.2563674-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.39.1.405.gd4c25cc71f-goog Message-ID: <20230124211455.2563674-3-dionnaglaze@google.com> Subject: [PATCH v13 2/4] crypto: ccp - Name -1 return value as SEV_RET_NO_FW_CALL From: Dionna Glaze To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Peter Gonda , Thomas Lendacky , Paolo Bonzini , Joerg Roedel , Ingo Molnar , Andy Lutomirsky , John Allen , Herbert Xu , "David S. Miller" , Borislav Petkov , Dionna Glaze Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Peter Gonda The PSP can return a "firmware error" code of -1 in circumstances where the PSP is not actually called. To make this protocol unambiguous, the value is named SEV_RET_NO_FW_CALL. Cc: Thomas Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Ingo Molnar Cc: Andy Lutomirsky Cc: John Allen Cc: Herbert Xu Cc: "David S. Miller" Cc: Borislav Petkov Signed-off-by: Peter Gonda Signed-off-by: Dionna Glaze --- Documentation/virt/coco/sev-guest.rst | 2 +- drivers/crypto/ccp/sev-dev.c | 22 ++++++++++++++-------- include/uapi/linux/psp-sev.h | 7 +++++++ 3 files changed, 22 insertions(+), 9 deletions(-) diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coc= o/sev-guest.rst index bf593e88cfd9..e76393e389eb 100644 --- a/Documentation/virt/coco/sev-guest.rst +++ b/Documentation/virt/coco/sev-guest.rst @@ -41,7 +41,7 @@ The guest ioctl should be issued on a file descriptor of = the /dev/sev-guest devi The ioctl accepts struct snp_user_guest_request. The input and output stru= cture is specified through the req_data and resp_data field respectively. If the io= ctl fails to execute due to a firmware error, then fw_err code will be set otherwise= the -fw_err will be set to 0x00000000000000ff. +fw_err will be set to 0x00000000ffffffff, i.e., the lower 32-bits are -1. =20 The firmware checks that the message sequence counter is one greater than the guests message sequence counter. If guest driver fails to increment me= ssage diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 06fc7156c04f..ac205f78a595 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -440,12 +440,19 @@ static int __sev_init_ex_locked(int *error) return __sev_do_cmd_locked(SEV_CMD_INIT_EX, &data, error); } =20 +static inline int __sev_do_init_locked(int *psp_ret) +{ + if (sev_init_ex_buffer) + return __sev_init_ex_locked(psp_ret); + else + return __sev_init_locked(psp_ret); +} + static int __sev_platform_init_locked(int *error) { struct psp_device *psp =3D psp_master; struct sev_device *sev; - int rc =3D 0, psp_ret =3D -1; - int (*init_function)(int *error); + int rc =3D 0, psp_ret =3D SEV_RET_NO_FW_CALL; =20 if (!psp || !psp->sev_data) return -ENODEV; @@ -456,15 +463,12 @@ static int __sev_platform_init_locked(int *error) return 0; =20 if (sev_init_ex_buffer) { - init_function =3D __sev_init_ex_locked; rc =3D sev_read_init_ex_file(); if (rc) return rc; - } else { - init_function =3D __sev_init_locked; } =20 - rc =3D init_function(&psp_ret); + rc =3D __sev_do_init_locked(&psp_ret); if (rc && psp_ret =3D=3D SEV_RET_SECURE_DATA_INVALID) { /* * Initialization command returned an integrity check failure @@ -473,9 +477,11 @@ static int __sev_platform_init_locked(int *error) * initialization function should succeed by replacing the state * with a reset state. */ - dev_err(sev->dev, "SEV: retrying INIT command because of SECURE_DATA_INV= ALID error. Retrying once to reset PSP SEV state."); - rc =3D init_function(&psp_ret); + dev_err(sev->dev, +"SEV: retrying INIT command because of SECURE_DATA_INVALID error. Retrying= once to reset PSP SEV state."); + rc =3D __sev_do_init_locked(&psp_ret); } + if (error) *error =3D psp_ret; =20 diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h index 91b4c63d5cbf..e8cfb8bde0d7 100644 --- a/include/uapi/linux/psp-sev.h +++ b/include/uapi/linux/psp-sev.h @@ -36,6 +36,13 @@ enum { * SEV Firmware status code */ typedef enum { + /* + * This error code is not in the SEV spec but is added to convey that + * there was an error that prevented the SEV Firmware from being called. + * The SEV API error codes are 16 bits, so the -1 value will not overlap + * with possible values from the specification. + */ + SEV_RET_NO_FW_CALL =3D -1, SEV_RET_SUCCESS =3D 0, SEV_RET_INVALID_PLATFORM_STATE, SEV_RET_INVALID_GUEST_STATE, --=20 2.39.1.405.gd4c25cc71f-goog From nobody Sun Sep 14 09:38:55 2025 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 BBEFAC54EED for ; Tue, 24 Jan 2023 21:16:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234961AbjAXVQF (ORCPT ); Tue, 24 Jan 2023 16:16:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234850AbjAXVPl (ORCPT ); Tue, 24 Jan 2023 16:15:41 -0500 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 958BB51C67 for ; Tue, 24 Jan 2023 13:15:24 -0800 (PST) Received: by mail-pl1-x64a.google.com with SMTP id y20-20020a170902cad400b001962668ef33so226618pld.22 for ; Tue, 24 Jan 2023 13:15:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=+X4WI8Vg5FvkeEucjSrZTy41Z/xG5Iw7Mra+pbnKFLQ=; b=Oa+4Xo870btNY2WgQhHJW0J/kJ/wQb1RhIrufJTgSmLe5GscWzylh+/ibWVCTIUEgZ iGri+L5+KvyhMJ/1jj6NnJZbQ3Dsk1yuXb7QTl3iX93AfF6OxNKkxdb7sMxh8CfTgY33 2Cxb65ArUyZ03UWe/nBk5k+bhQ8c+1aHog0LUmyMRQeNT8FPOYntPIzgLG15E3Qh/qpD cuwxmhYnYWU0lVOcx68A5wt+YOQGhDBktoNbVCTZnUbYvr8MeymMC/O0BeJ1FedI/BMy yeU7EBSR+ffX5CQJ2ykgEpYVlKeYCucS15Qwfb1MHBdC1da4dvnJNmeQYUto9rhQSIew mRew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+X4WI8Vg5FvkeEucjSrZTy41Z/xG5Iw7Mra+pbnKFLQ=; b=1uCQl5MOYsZ93KMqTDxL4LerexogtLgrkcoEjXanf9zYtdf2FbwVbSuoERgIFfw/De YGBokjOlIrJsGOC/T/mVqJRBoe+2tdCQjY0McK1EE/39aqqdZbMAyv0SUhH8HSO+N0oL Gly5F2xhDvBko6AoiY11zU2QMSw5YDUaNmqUi8+niOO11LHMmMpXjP3e+1tTypdMzPQs s81yAUXJXewpHoAmlg4+65MLmp8nbMSbVyj5iUd/4WbToxypleZ2eB05QlkX9qztBY6n VcQPFYlxPITXqGuXtSWrj1v17nELAwgYVee2HTYuTbJssdipmYZ/npPmkaVEkQ0Zb922 OcKQ== X-Gm-Message-State: AFqh2komVreLOwvwusbdoiTAYWqyGqxYv58JMpONxxXc5DG0uNzVtbw0 i6oEcXdcZg5FKO/QAzB89L4UTccudeSiiImvg65ok0rjwBr/ai17q/G84g7YTvIfwxfjBdJdjFn hAPLoC/Vrk4Z12n4wb6IwWwKsjb1nogoPenyGgLlZbVRrhhICD7/m5rHRXHHn4/6K6k3vDmJ5es dVXDdCpmc= X-Google-Smtp-Source: AMrXdXtfsjHrA4b6YYJG6jEh5J8d8jAuqx7uZV5FWy6HIY8IMiTc4tThPfZQK5Np0Ez3Spz5+rJo0OunJjAARdQmyA== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a63:5:0:b0:46f:cbcb:761a with SMTP id 5-20020a630005000000b0046fcbcb761amr1407336pga.82.1674594923491; Tue, 24 Jan 2023 13:15:23 -0800 (PST) Date: Tue, 24 Jan 2023 21:14:54 +0000 In-Reply-To: <20230124211455.2563674-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20230124211455.2563674-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.39.1.405.gd4c25cc71f-goog Message-ID: <20230124211455.2563674-4-dionnaglaze@google.com> Subject: [PATCH v13 3/4] x86/sev: Change snp_guest_issue_request's fw_err 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 , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Venu Busireddy , Michael Roth , "Kirill A. Shutemov" , Michael Sterritt Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The GHCB specification declares that the firmware error value for a guest request will be stored in the lower 32 bits of EXIT_INFO_2. The upper 32 bits are for the VMM's own error code. The fw_err argument is thus a misnomer, and callers will need access to all 64 bits. The type of unsigned long also causes problems, since sw_exit_info2 is u64 (unsigned long long) vs the argument's unsigned long*. This type is changed for issuing the guest request. The ioctl command struct's error field is passed directly instead of a local variable, since an incomplete guest request may not set the error code, and uninitialized stack memory would be written back to user space. The firmware might not even be called, so the call is bookended with the no firmware call error and clearing the error. Since the "fw_err" field is really exitinfo2 split into the upper bits' vmm error code and lower bits' firmware error code, sev-guest.h is updated to represent the 64 bit value as a union. Cc: Tom Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Peter Gonda Cc: Thomas Gleixner Cc: Dave Hansen Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Venu Busireddy Cc: Michael Roth Cc: "Kirill A. Shutemov" Cc: Michael Sterritt Signed-off-by: Dionna Glaze --- Documentation/virt/coco/sev-guest.rst | 21 +++++++---- arch/x86/include/asm/sev-common.h | 4 -- arch/x86/include/asm/sev.h | 4 +- arch/x86/kernel/sev.c | 12 ++++-- drivers/virt/coco/sev-guest/sev-guest.c | 50 ++++++++++++------------- include/uapi/linux/sev-guest.h | 18 ++++++++- 6 files changed, 64 insertions(+), 45 deletions(-) diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coc= o/sev-guest.rst index e76393e389eb..48e89ea2a618 100644 --- a/Documentation/virt/coco/sev-guest.rst +++ b/Documentation/virt/coco/sev-guest.rst @@ -37,11 +37,12 @@ along with a description: the return value. General error numbers (-ENOMEM, -EINVAL) are not detailed, but errors with specific meanings are. =20 -The guest ioctl should be issued on a file descriptor of the /dev/sev-gues= t device. -The ioctl accepts struct snp_user_guest_request. The input and output stru= cture is -specified through the req_data and resp_data field respectively. If the io= ctl fails -to execute due to a firmware error, then fw_err code will be set otherwise= the -fw_err will be set to 0x00000000ffffffff, i.e., the lower 32-bits are -1. +The guest ioctl should be issued on a file descriptor of the +/dev/sev-guest device. The ioctl accepts struct +snp_user_guest_request. The input and output structure is specified +through the req_data and resp_data field respectively. If the ioctl +fails to execute due to a firmware error, then the fw_error code will +be set, otherwise fw_error will be set to -1. =20 The firmware checks that the message sequence counter is one greater than the guests message sequence counter. If guest driver fails to increment me= ssage @@ -57,8 +58,14 @@ counter (e.g. counter overflow), then -EIO will be retur= ned. __u64 req_data; __u64 resp_data; =20 - /* firmware error code on failure (see psp-sev.h) */ - __u64 fw_err; + /* bits[63:32]: VMM error code, bits[31:0] firmware error = code (see psp-sev.h) */ + union { + __u64 exitinfo2; + struct { + __u32 fw_error; + __u32 vmm_error; + }; + }; }; =20 2.1 SNP_GET_REPORT diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-c= ommon.h index b63be696b776..0759af9b1acf 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -128,10 +128,6 @@ struct snp_psc_desc { struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY]; } __packed; =20 -/* Guest message request error codes */ -#define SNP_GUEST_REQ_INVALID_LEN BIT_ULL(32) -#define SNP_GUEST_REQ_ERR_BUSY BIT_ULL(33) - #define GHCB_MSR_TERM_REQ 0x100 #define GHCB_MSR_TERM_REASON_SET_POS 12 #define GHCB_MSR_TERM_REASON_SET_MASK 0xf diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index ebc271bb6d8e..05de34d10d89 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -196,7 +196,7 @@ void snp_set_memory_private(unsigned long vaddr, unsign= ed int npages); void snp_set_wakeup_secondary_cpu(void); bool snp_init(struct boot_params *bp); void __init __noreturn snp_abort(void); -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, uns= igned long *fw_err); +int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, u64= *exitinfo2); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -217,7 +217,7 @@ static inline void snp_set_wakeup_secondary_cpu(void) {= } static inline bool snp_init(struct boot_params *bp) { return false; } static inline void snp_abort(void) { } static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_da= ta *input, - unsigned long *fw_err) + u64 *exitinfo2) { return -ENOTTY; } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index a908ffc2dfba..82aa81fafb71 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -22,6 +22,8 @@ #include #include #include +#include +#include =20 #include #include @@ -2175,7 +2177,7 @@ static int __init init_sev_config(char *str) } __setup("sev=3D", init_sev_config); =20 -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, uns= igned long *fw_err) +int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, u64= *exitinfo2) { struct ghcb_state state; struct es_em_ctxt ctxt; @@ -2186,9 +2188,11 @@ int snp_issue_guest_request(u64 exit_code, struct sn= p_req_data *input, unsigned if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; =20 - if (!fw_err) + if (!exitinfo2) return -EINVAL; =20 + *exitinfo2 =3D SEV_RET_NO_FW_CALL; + /* * __sev_get_ghcb() needs to run with IRQs disabled because it is using * a per-CPU GHCB. @@ -2212,11 +2216,11 @@ int snp_issue_guest_request(u64 exit_code, struct s= np_req_data *input, unsigned if (ret) goto e_put; =20 - *fw_err =3D ghcb->save.sw_exit_info_2; + *exitinfo2 =3D ghcb->save.sw_exit_info_2; if (ghcb->save.sw_exit_info_2) { /* Number of expected pages are returned in RBX */ if (exit_code =3D=3D SVM_VMGEXIT_EXT_GUEST_REQUEST && - ghcb->save.sw_exit_info_2 =3D=3D SNP_GUEST_REQ_INVALID_LEN) + ghcb->save.sw_exit_info_2 =3D=3D SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_IN= VALID_LEN)) input->data_npages =3D ghcb_get_rbx(ghcb); =20 ret =3D -EIO; diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index 3d6551fdf06f..e82f080aa679 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -318,11 +318,11 @@ static int enc_payload(struct snp_guest_dev *snp_dev,= u64 seqno, int version, u8 return __enc_payload(snp_dev, req, payload, sz); } =20 -static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_co= de, int msg_ver, - u8 type, void *req_buf, size_t req_sz, void *resp_buf, - u32 resp_sz, __u64 *fw_err) +static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_co= de, + struct snp_guest_request_ioctl *arg, + u8 type, void *req_buf, size_t req_sz, + void *resp_buf, u32 resp_sz) { - unsigned long err =3D 0xff; u64 seqno; int rc; =20 @@ -334,7 +334,7 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); =20 /* Encrypt the userspace provided payload */ - rc =3D enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz); + rc =3D enc_payload(snp_dev, seqno, arg->msg_version, type, req_buf, req_s= z); if (rc) return rc; =20 @@ -345,14 +345,15 @@ static int handle_guest_request(struct snp_guest_dev = *snp_dev, u64 exit_code, in * sequence number must be incremented or the VMPCK must be deleted to * prevent reuse of the IV. */ - rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); + rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, + &arg->exitinfo2); =20 /* - * The host may return SNP_GUEST_REQ_ERR_EBUSY if the request has been + * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been * throttled. Retry in the driver to avoid returning and reusing the * message sequence number on a different message. */ - if (err =3D=3D SNP_GUEST_REQ_ERR_BUSY) + if (arg->vmm_error =3D=3D SNP_GUEST_VMM_ERR_BUSY) goto retry; =20 /* @@ -362,7 +363,7 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in * and thus avoid IV reuse. */ if (exit_code =3D=3D SVM_VMGEXIT_EXT_GUEST_REQUEST && - err =3D=3D SNP_GUEST_REQ_INVALID_LEN) { + arg->vmm_error =3D=3D SNP_GUEST_VMM_ERR_INVALID_LEN) { const unsigned int certs_npages =3D snp_dev->input.data_npages; =20 exit_code =3D SVM_VMGEXIT_GUEST_REQUEST; @@ -375,24 +376,22 @@ static int handle_guest_request(struct snp_guest_dev = *snp_dev, u64 exit_code, in * of the VMPCK and the error code being propagated back to the * user as an ioctl() return code. */ - rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); + rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, + &arg->exitinfo2); =20 /* * Override the error to inform callers the given extended * request buffer size was too small and give the caller the * required buffer size. */ - err =3D SNP_GUEST_REQ_INVALID_LEN; + arg->vmm_error =3D SNP_GUEST_VMM_ERR_INVALID_LEN; snp_dev->input.data_npages =3D certs_npages; } =20 - if (fw_err) - *fw_err =3D err; - if (rc) { dev_alert(snp_dev->dev, - "Detected error from ASP request. rc: %d, fw_err: %llu\n", - rc, *fw_err); + "Detected error from ASP request. rc: %d, exitinfo2: %llx\n", + rc, arg->exitinfo2); goto disable_vmpck; } =20 @@ -439,9 +438,9 @@ static int get_report(struct snp_guest_dev *snp_dev, st= ruct snp_guest_request_io if (!resp) return -ENOMEM; =20 - rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_= version, + rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data, - resp_len, &arg->fw_err); + resp_len); if (rc) goto e_free; =20 @@ -479,9 +478,8 @@ static int get_derived_key(struct snp_guest_dev *snp_de= v, struct snp_guest_reque if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) return -EFAULT; =20 - rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_= version, - SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len, - &arg->fw_err); + rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, + SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len); if (rc) return rc; =20 @@ -541,12 +539,12 @@ static int get_ext_report(struct snp_guest_dev *snp_d= ev, struct snp_guest_reques return -ENOMEM; =20 snp_dev->input.data_npages =3D npages; - ret =3D handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg-= >msg_version, + ret =3D handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, &req.data, - sizeof(req.data), resp->data, resp_len, &arg->fw_err); + sizeof(req.data), resp->data, resp_len); =20 /* If certs length is invalid then copy the returned length */ - if (arg->fw_err =3D=3D SNP_GUEST_REQ_INVALID_LEN) { + if (arg->vmm_error =3D=3D SNP_GUEST_VMM_ERR_INVALID_LEN) { req.certs_len =3D snp_dev->input.data_npages << PAGE_SHIFT; =20 if (copy_to_user((void __user *)arg->req_data, &req, sizeof(req))) @@ -581,7 +579,7 @@ static long snp_guest_ioctl(struct file *file, unsigned= int ioctl, unsigned long if (copy_from_user(&input, argp, sizeof(input))) return -EFAULT; =20 - input.fw_err =3D 0xff; + input.exitinfo2 =3D 0xff; =20 /* Message version must be non-zero */ if (!input.msg_version) @@ -612,7 +610,7 @@ static long snp_guest_ioctl(struct file *file, unsigned= int ioctl, unsigned long =20 mutex_unlock(&snp_cmd_mutex); =20 - if (input.fw_err && copy_to_user(argp, &input, sizeof(input))) + if (input.exitinfo2 && copy_to_user(argp, &input, sizeof(input))) return -EFAULT; =20 return ret; diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h index 256aaeff7e65..2aa39112cf8d 100644 --- a/include/uapi/linux/sev-guest.h +++ b/include/uapi/linux/sev-guest.h @@ -52,8 +52,14 @@ struct snp_guest_request_ioctl { __u64 req_data; __u64 resp_data; =20 - /* firmware error code on failure (see psp-sev.h) */ - __u64 fw_err; + /* bits[63:32]: VMM error code, bits[31:0] firmware error code (see psp-s= ev.h) */ + union { + __u64 exitinfo2; + struct { + __u32 fw_error; + __u32 vmm_error; + }; + }; }; =20 struct snp_ext_report_req { @@ -77,4 +83,12 @@ struct snp_ext_report_req { /* Get SNP extended report as defined in the GHCB specification version 2.= */ #define SNP_GET_EXT_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x2, struct snp_g= uest_request_ioctl) =20 +/* Guest message request EXIT_INFO_2 constants */ +#define SNP_GUEST_FW_ERR_MASK GENMASK_ULL(31, 0) +#define SNP_GUEST_VMM_ERR_SHIFT 32 +#define SNP_GUEST_VMM_ERR(x) (((u64)x) << SNP_GUEST_VMM_ERR_SHIFT) + +#define SNP_GUEST_VMM_ERR_INVALID_LEN 1 +#define SNP_GUEST_VMM_ERR_BUSY 2 + #endif /* __UAPI_LINUX_SEV_GUEST_H_ */ --=20 2.39.1.405.gd4c25cc71f-goog From nobody Sun Sep 14 09:38:55 2025 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 26ACAC54E94 for ; Tue, 24 Jan 2023 21:16:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234971AbjAXVQH (ORCPT ); Tue, 24 Jan 2023 16:16:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234899AbjAXVPp (ORCPT ); Tue, 24 Jan 2023 16:15:45 -0500 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FE57521C1 for ; Tue, 24 Jan 2023 13:15:25 -0800 (PST) Received: by mail-pj1-x104a.google.com with SMTP id h6-20020a17090aa88600b00223fccff2efso11723723pjq.6 for ; Tue, 24 Jan 2023 13:15:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=JBzFUdybILoe8O9craXfERpc0jtsf4nQJK8kxIB3j/E=; b=EVNMKlTM19LGYN9Zq7dvfNaMSXJvWYcRRygrmiGp1NbryTDgQBhofHKxEGEzrApKBB ydVvCwPs2gj7utggt4WMvX7N+ydAP+7E4mBGnIKPxP4tutVrbkhYqFBlSIH8N0nWsGUs pXhVWeiWFCkyZCYGqGtlPdnaLsUlZe1suiEOxLJCXyYBNrbEqYtSG6UCRm98UM4IhYAN h3Pke9usobrHnyOylpVGk8sXT/SSk196OK0Yw+l0Ta/4MnkTyCzeqmw37aWNHU1kJTG9 dLtwKI/wXDG+aWCSEz/lLxcwCPYMSy5Ro15+5qnU4h6ryBjbT801cnFDHwwUSGT8vSLy z2og== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=JBzFUdybILoe8O9craXfERpc0jtsf4nQJK8kxIB3j/E=; b=q/9Y4y7odRCv5up5Q90zl+VM8xGPBFCgc+B6RLNl/HkwKA7XG15O+JJ7L+9lHis8tG VzjZxy7ZtjthWAjPjyj/IbtoFsu86IosP4yWRQtJHUn5IrOWNeyNe7bzopk3Ab3c9kwB OnByPnMyAUUoDXXLxCWcqwU14DLRu9S/v5/uAFaynLzm96UDroT0R2eZdncbMO8YO7Tx n2B5rUBlUlpzLNMQ99fAEYp7JwMiyGqem63gkNHkUMjJWUWrjTSx+uBWD2NhvsMeCF6y Ee7JKJsDdvx2BKn2Jcdx2SsWShAz1iuZU5qiJ0KA7LicsBPITNS72GRTZQSGOVtbhyB2 SnuQ== X-Gm-Message-State: AFqh2krMaUtZ3wqRC4VU5v5SN8FaqOwN+/SbYGSi2/CgUkr34LxOZqJT P4Pl7uLlUcwJVufnFnLZdCHqwOhXY1WApuMh2a9UsPC2BBeBYPPZfMrgCFnL8ZZ9MtYhTt15k2g dl//5Va8QF4NCpeabQAofuwJBnfqzJUarX8V74BPa0YZCaoChVtuvHrp2A39X44JfrfMInbb9Dc 2tAhpaVtM= X-Google-Smtp-Source: AMrXdXs/rxPJO88KcgHzbLzGJJs/MW4Rg+/YmGZes573wdJg2Tif+mJ60qHw/sdJ7o5aZmZ3tSWphfQu10KE5V8Wvw== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a17:902:6acc:b0:187:3921:2b2d with SMTP id i12-20020a1709026acc00b0018739212b2dmr2968716plt.13.1674594924957; Tue, 24 Jan 2023 13:15:24 -0800 (PST) Date: Tue, 24 Jan 2023 21:14:55 +0000 In-Reply-To: <20230124211455.2563674-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20230124211455.2563674-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.39.1.405.gd4c25cc71f-goog Message-ID: <20230124211455.2563674-5-dionnaglaze@google.com> Subject: [PATCH v13 4/4] virt: sev-guest: self-throttle guest request retries From: Dionna Glaze To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Dionna Glaze , Tom Lendacky , Peter Gonda , Borislav Petkov , Tom Lendacky , Liam Merwick , Yang Yingliang , Haowen Bai Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When throttled, the driver will reschedule itself and then try again after sleeping half its ratelimit time to avoid a big wait queue. The ioctl may block indefinitely, but that has always been the case when deferring these requests to the host. Cc: Tom Lendacky Cc: Peter Gonda Cc: Borislav Petkov Cc: Tom Lendacky Cc: Liam Merwick Cc: Yang Yingliang Cc: Haowen Bai Signed-off-by: Dionna Glaze --- drivers/virt/coco/sev-guest/sev-guest.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index e82f080aa679..af0645f40e95 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -48,12 +49,22 @@ struct snp_guest_dev { struct snp_req_data input; u32 *os_area_msg_seqno; u8 *vmpck; + + struct ratelimit_state rs; }; =20 static u32 vmpck_id; module_param(vmpck_id, uint, 0444); MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with th= e PSP."); =20 +static int rate_s =3D 1; +module_param(rate_s, int, 0444); +MODULE_PARM_DESC(rate_s, "The rate limit interval in seconds to limit requ= ests to."); + +static int rate_burst =3D 2; +module_param(rate_burst, int, 0444); +MODULE_PARM_DESC(rate_burst, "The rate limit burst amount to limit request= s to."); + /* Mutex to serialize the shared buffer access and command handling. */ static DEFINE_MUTEX(snp_cmd_mutex); =20 @@ -339,6 +350,15 @@ static int handle_guest_request(struct snp_guest_dev *= snp_dev, u64 exit_code, return rc; =20 retry: + /* + * Rate limit commands internally since the host can also throttle, and + * the guest shouldn't create a tight request spin that could end up + * getting this VM throttled more heavily. + */ + if (!__ratelimit(&snp_dev->rs)) { + schedule_timeout_interruptible((rate_s * HZ) / 2); + goto retry; + } /* * Call firmware to process the request. In this function the encrypted * message enters shared memory with the host. So after this call the @@ -760,6 +780,8 @@ static int __init sev_guest_probe(struct platform_devic= e *pdev) if (ret) goto e_free_cert_data; =20 + ratelimit_state_init(&snp_dev->rs, rate_s * HZ, rate_burst); + dev_info(dev, "Initialized SEV guest driver (using vmpck_id %d)\n", vmpck= _id); return 0; =20 --=20 2.39.1.405.gd4c25cc71f-goog