From nobody Thu Apr 9 10:53:49 2026 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 9A60CC433FE for ; Fri, 4 Nov 2022 20:16:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229918AbiKDUQe (ORCPT ); Fri, 4 Nov 2022 16:16:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229866AbiKDUQb (ORCPT ); Fri, 4 Nov 2022 16:16:31 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A14D45ECA for ; Fri, 4 Nov 2022 13:16:30 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-3697bd55974so55304827b3.15 for ; Fri, 04 Nov 2022 13:16:30 -0700 (PDT) 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=vzksqxZzngSMnVq4LNIxjbY1eQuHqjVmZsqNyLkHpLQ=; b=jhPIbPD5BQTq81GOSTK237jTlF2fdO6oPYPy+cM2vMFS3sS/w17VHxLXqWaLre2baw Dg7vRG1TECmSbDjloLx5MYR0wTohEYRdFSI6Le9y/hLxMWYStbgHTcS/8BEY0Mye6mQM 5RcisHx3NbfpWxsqiQ73t9SFwtfVCqnRVuNd39fTiWo93R/G3mXGXiaoqMQS7qT7C49Z /RffMJbCcphU6MVtcGMdXHMCWzCx/6NfqoO7JfmYlrdAkYtyB7WlsWnIPM+KAVphsdCM +9Rbm6jEmHJa6iqME4PmT4m0vVBdJGcKfoL+JYMwGtFUikhaeAxiyeEr0rPSJSvn+bNu R+6g== 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=vzksqxZzngSMnVq4LNIxjbY1eQuHqjVmZsqNyLkHpLQ=; b=6bx/LiigbMv8R+oAgDzxAPgUAVPtRaf0sSTJD6E/l4GJCh2zEpvR3KHOvnxwAwQiVN qBfdXRV36QH5/NbXaL8ifv9QObe/jlxqluUum0CNkq5q6K/s6MTNCcMl9rwndeMhPsHF 4dFjDMRo7gizRLLDydULrECouafHGCePQCJcvr9twXfnueUxR5yV+szTyPOip/KIG8lD fBLKIdgOGg4xcpe1VK1MZWYhl8rbxvdMUb0lYFYcEzcmDrfHt5DSu0vGjGWXbsTYQs/W KfM07+vNSQu8v1CYkgf0ttEYDQQ3mS54VX6zhY2xjBCikcxoDiH6s6s0r9P96oHJ40sA NQRw== X-Gm-Message-State: ACrzQf1FYV5PiRchYe5NcQWN6UkQumtzOWCXWMMhANjkMashHGasGdem MfgkMHN390RanhculwZFRkPzNlEjCpe+iYYMtCcnk+uyRRUAWQl3Pv0tmwLx8GxQhgd5gqjTrHf 7VM3pBjoTn/yJ4Orc5PtHLIxtzoLn/jIYD2MpRt0OGIDJJ0PNlYd+kM9asWFiakSXBtmH/Xlgpm gl8kgsamg= X-Google-Smtp-Source: AMsMyM5X0sev4Pv04ITUvgt8NibKSAXimserJ6yKIuWolEr0LKxTvByNxl3a3Cmotpmx+rxeQUHTsncxkcLRCVCsnQ== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a25:9d11:0:b0:66e:4fad:e153 with SMTP id i17-20020a259d11000000b0066e4fade153mr35592854ybp.484.1667592989294; Fri, 04 Nov 2022 13:16:29 -0700 (PDT) Date: Fri, 4 Nov 2022 20:16:13 +0000 In-Reply-To: <20221104201616.2268815-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20221104201616.2268815-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221104201616.2268815-2-dionnaglaze@google.com> Subject: [PATCH v7 1/4] 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" , 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, we add a constant naming the return value. 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" Signed-off-by: Peter Gonda Signed-off-by: Dionna Glaze --- drivers/crypto/ccp/sev-dev.c | 2 +- include/uapi/linux/psp-sev.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 06fc7156c04f..97eb3544ab36 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -444,7 +444,7 @@ 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 rc =3D 0, psp_ret =3D SEV_RET_NO_FW_CALL; int (*init_function)(int *error); =20 if (!psp || !psp->sev_data) diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h index 91b4c63d5cbf..1ad7f0a7e328 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. + * This is (u32)-1 since the firmware error code is represented as a + * 32-bit integer. + */ + SEV_RET_NO_FW_CALL =3D 0xffffffff, SEV_RET_SUCCESS =3D 0, SEV_RET_INVALID_PLATFORM_STATE, SEV_RET_INVALID_GUEST_STATE, --=20 2.38.1.431.g37b22c650d-goog From nobody Thu Apr 9 10:53:49 2026 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 C9966C4332F for ; Fri, 4 Nov 2022 20:16:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229911AbiKDUQn (ORCPT ); Fri, 4 Nov 2022 16:16:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229906AbiKDUQc (ORCPT ); Fri, 4 Nov 2022 16:16:32 -0400 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 CE34045EDE for ; Fri, 4 Nov 2022 13:16:31 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id f189-20020a6238c6000000b0056e3400fdc0so2941197pfa.10 for ; Fri, 04 Nov 2022 13:16:31 -0700 (PDT) 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=Kw7Ul5f27jSNcm6KBKc7sXnYAWm8yJrh7zk3qUYUCYY=; b=Il1wC+xW4V9ldzvEHntjxeveeNBukzQwgnx6gzRlwbIvwfuGMJVlqiruprMfTz88Dd xvy5YV5RGoMrccjmm31d0Qom8iTNLwQpVpZ98/re1X218bG9GO+98pG2U5CPoH4U8Eqy FDoJjtaLe1MXJv3LhC0UumN5tvBzw44DeHfxvRkE7KXEP+LYLXb096fcc5UFs2x8zRkU LBUTP6TCP2mcB4fQEVYnxM6k6iUgpW016AazEVmWLE9D5DqriUS5/LoH3OIBmvSVvp6X A9CF6Jf7YRsPzoXPkhcnwgFrHIwKgc379OqRVqTghG2vfDiAd3661KiYlMyGOpUZ02CI xgNw== 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=Kw7Ul5f27jSNcm6KBKc7sXnYAWm8yJrh7zk3qUYUCYY=; b=sOA/xoa5azVvW0MzICnIn1pT+FKX/ioJbGrM3CnxUubnrM8PGipJl5vHd6D7GQf3gq yJSGH+yqTD/n03CROgr50O/5J6A9GXf/pQhIg8ZNwfVWxjH6vzSRoRApx3wwiol0yRdD m4duMJGLZ56RZ5rtLFjX8q85CyYSgXsNNz3ltbdAWT2abJXC+DgmSwP74EPbA3rB53Lx ttE0PKm1ntU7Mhw0hZX8ijHFpKdFwvvBq9yzF/3SuqwHLPekIxz0FcFLcM82jNJCxMfz CoerRqV41bSN6h1VPrWJfU5esjPfDfptB1U6ULtORDapZeoHrwj6tY9FDpB1tPhAqyQ2 JbTQ== X-Gm-Message-State: ACrzQf3Bh1ik2CCwZg9mgNYAmkw2sfhaE6/+KOSDZVCe9jS5Rm9NiWeM A6/j6PA9t74ONXP86T9SLaG4UI2y/igtHYh6l+cu7bjjXJ/9eQawe4Q/JDoon3KzpomszcL9t3b LDduP9zGJuyKffFZ0IRu9ookTUEzxiqznTp7f2YppjlfD73JhjyH9oJXUQGKGofO4UlOuiiYGjH 0gq8RdLd0= X-Google-Smtp-Source: AMsMyM4GgyBoekcX1bBRDD+sWG0dLd823DITt4nxbL4V22LF2TrKZ3AJxz/vhte1Yzl335VWqptHYiH9KRZW7MYdFw== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a17:90a:df8e:b0:213:8283:ac7f with SMTP id p14-20020a17090adf8e00b002138283ac7fmr356850pjv.220.1667592991086; Fri, 04 Nov 2022 13:16:31 -0700 (PDT) Date: Fri, 4 Nov 2022 20:16:14 +0000 In-Reply-To: <20221104201616.2268815-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20221104201616.2268815-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221104201616.2268815-3-dionnaglaze@google.com> Subject: [PATCH v7 2/4] 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 previous unsigned long*. The signature change requires the follow-up change to drivers/virt/coco/sev-guest to use the new expected type in order to compile. The firmware might not even be called, so we bookend the call with the no firmware call error and clearing the error. 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 Reviewed-by: Peter Gonda --- arch/x86/include/asm/sev.h | 4 ++-- arch/x86/kernel/sev.c | 10 ++++++---- 2 files changed, 8 insertions(+), 6 deletions(-) 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 a428c62330d3..148f17cb07b5 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -22,6 +22,7 @@ #include #include #include +#include =20 #include #include @@ -2175,7 +2176,7 @@ 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 +2187,11 @@ 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. @@ -2212,14 +2215,13 @@ int snp_issue_guest_request(u64 exit_code, struct s= np_req_data *input, unsigned if (ret) goto e_put; =20 + *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) input->data_npages =3D ghcb_get_rbx(ghcb); =20 - *fw_err =3D ghcb->save.sw_exit_info_2; - ret =3D -EIO; } =20 --=20 2.38.1.431.g37b22c650d-goog From nobody Thu Apr 9 10:53:49 2026 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 2808AC433FE for ; Fri, 4 Nov 2022 20:16:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229959AbiKDUQp (ORCPT ); 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Fri, 04 Nov 2022 13:16:33 -0700 (PDT) Date: Fri, 4 Nov 2022 20:16:15 +0000 In-Reply-To: <20221104201616.2268815-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20221104201616.2268815-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221104201616.2268815-4-dionnaglaze@google.com> Subject: [PATCH v7 3/4] virt: sev-guest: Remove err in handle_guest_request 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 , Borislav Petkov , Haowen Bai , Liam Merwick , Yang Yingliang 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 err variable may not be set in the call to snp_issue_guest_request, yet it is unconditionally written back to fw_err if fw_err is non-null. This is undefined behavior, and currently returns uninitialized kernel stack memory to user space. The fw_err argument is better to just pass through to snp_issue_guest_request, so we do that. Since the issue_request's signature has changed fw_err to exitinfo2, we change the argument name here. Cc: Tom Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Peter Gonda Cc: Thomas Gleixner Cc: Dave Hansen Cc: Borislav Petkov Cc: Haowen Bai Cc: Liam Merwick Cc: Yang Yingliang Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Signed-off-by: Dionna Glaze --- drivers/virt/coco/sev-guest/sev-guest.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index d08ff87c2dac..5ebf87651299 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -322,9 +322,8 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u= 64 seqno, int version, u8 =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) + u32 resp_sz, __u64 *exitinfo2) { - unsigned long err; u64 seqno; int rc; =20 @@ -341,7 +340,7 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in return rc; =20 /* Call firmware to process the request */ - rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); + rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, exitinfo2); =20 /* * If the extended guest request fails due to having to small of a @@ -349,19 +348,16 @@ static int handle_guest_request(struct snp_guest_dev = *snp_dev, u64 exit_code, in * extended data request. */ if (exit_code =3D=3D SVM_VMGEXIT_EXT_GUEST_REQUEST && - err =3D=3D SNP_GUEST_REQ_INVALID_LEN) { + *exitinfo2 =3D=3D SNP_GUEST_REQ_INVALID_LEN) { const unsigned int certs_npages =3D snp_dev->input.data_npages; =20 exit_code =3D SVM_VMGEXIT_GUEST_REQUEST; - rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); + rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, exitinfo2); =20 - err =3D SNP_GUEST_REQ_INVALID_LEN; + *exitinfo2 =3D SNP_GUEST_REQ_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", --=20 2.38.1.431.g37b22c650d-goog From nobody Thu Apr 9 10:53:49 2026 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 B996DC433FE for ; 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Fri, 04 Nov 2022 13:16:34 -0700 (PDT) Date: Fri, 4 Nov 2022 20:16:16 +0000 In-Reply-To: <20221104201616.2268815-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20221104201616.2268815-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221104201616.2268815-5-dionnaglaze@google.com> Subject: [PATCH v7 4/4] virt: sev-guest: interpret VMM errors from guest request 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" The GHCB specification states that the upper 32 bits of exitinfo2 are for the VMM's error codes. The sev-guest ABI has already locked in that the fw_err status of the input will be 64 bits, and that BIT_ULL(32) means that the extended guest request's data buffer was too small, so we have to keep that ABI. We can still interpret the upper 32 bits of exitinfo2 for the user anyway in case the request gets throttled. For safety, since the encryption algorithm in GHCBv2 is AES_GCM, we cannot return to user space without having completed the request with the current sequence number. If we were to return and the guest were to make another request but with different message contents, then that would be IV reuse. 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 | 51 ++++++++++++++++++++----- include/uapi/linux/sev-guest.h | 18 ++++++++- 2 files changed, 58 insertions(+), 11 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index 5ebf87651299..9c49f38aba44 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 @@ -324,6 +335,7 @@ 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 *exitinfo2) { + unsigned int vmm_err; u64 seqno; int rc; =20 @@ -339,16 +351,35 @@ static int handle_guest_request(struct snp_guest_dev = *snp_dev, u64 exit_code, in if (rc) return rc; =20 +retry: + /* + * Rate limit commands internally since the host can also throttle, and + * we don't want to 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 */ rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, exitinfo2); =20 + vmm_err =3D *exitinfo2 >> SNP_GUEST_VMM_ERR_SHIFT; + /* + * The host may return EBUSY if the request has been throttled. + * We retry in the driver to avoid returning and reusing the message + * sequence number on a different message. + */ + if (vmm_err =3D=3D SNP_GUEST_VMM_ERR_BUSY) + goto retry; + /* * If the extended guest request fails due to having to small of a * certificate data buffer retry the same guest request without the * extended data request. */ if (exit_code =3D=3D SVM_VMGEXIT_EXT_GUEST_REQUEST && - *exitinfo2 =3D=3D SNP_GUEST_REQ_INVALID_LEN) { + vmm_err =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; @@ -360,8 +391,8 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in =20 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: %llu\n", + rc, *exitinfo2); goto disable_vmpck; } =20 @@ -410,7 +441,7 @@ static int get_report(struct snp_guest_dev *snp_dev, st= ruct snp_guest_request_io =20 rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_= version, SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data, - resp_len, &arg->fw_err); + resp_len, &arg->exitinfo2); if (rc) goto e_free; =20 @@ -450,7 +481,7 @@ static int get_derived_key(struct snp_guest_dev *snp_de= v, struct snp_guest_reque =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); + &arg->exitinfo2); if (rc) return rc; =20 @@ -512,10 +543,10 @@ static int get_ext_report(struct snp_guest_dev *snp_d= ev, struct snp_guest_reques snp_dev->input.data_npages =3D npages; ret =3D handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg-= >msg_version, SNP_MSG_REPORT_REQ, &req.data, - sizeof(req.data), resp->data, resp_len, &arg->fw_err); + sizeof(req.data), resp->data, resp_len, &arg->exitinfo2); =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))) @@ -550,7 +581,7 @@ 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 SEV_RET_NO_FW_CALL; =20 /* Message version must be non-zero */ if (!input.msg_version) @@ -581,7 +612,7 @@ 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; @@ -731,6 +762,8 @@ 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 diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h index 256aaeff7e65..8e4144aa78c9 100644 --- a/include/uapi/linux/sev-guest.h +++ b/include/uapi/linux/sev-guest.h @@ -52,8 +52,15 @@ 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; + __u64 fw_err; /* Name deprecated in favor of others */ + struct { + __u32 fw_error; + __u32 vmm_error; + }; + }; }; =20 struct snp_ext_report_req { @@ -77,4 +84,11 @@ 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_INVALID_LEN 1 +#define SNP_GUEST_VMM_ERR_BUSY 2 + #endif /* __UAPI_LINUX_SEV_GUEST_H_ */ --=20 2.38.1.431.g37b22c650d-goog