From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) (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 EF58D34F47E for ; Thu, 29 Jan 2026 20:25:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.180.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769718314; cv=none; b=W1O6pzXPAhz5WXfeYJwB4cSu1dTueyOSLrzvd437HuaYtRcX+D3X6OQXNLS7OeCFFtrHf/FnsKd497gxLOiaBy9sUR1qYeEuASvqw/WGMHy2G1dofQASQljyCCPZE1OHSFLQuM0/iZZQ3BfY2npzARPRt75SH/CO5Z1mxTvr3h0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769718314; c=relaxed/simple; bh=v/AZkG/28KlNhb9unjxf+fqtqEO0ZP93Qeegkhk42mQ=; h=Mime-Version:Content-Type:Date:Message-Id:From:Subject:Cc:To: References:In-Reply-To; b=BTnSMkq9ijLMPqwEShpqzVZxwVOtd9KPCqxP1BpPqDfDxUn/CA9GySSM8vnej+p8lTP0pUw7aEd/1xi/nBoB8YWz0jX/oA8w2JdWmAvXwqC+uMK46Ng/cmp4TG2ifa8eVqEDlz9t/9tgAMvqppAAmpFE4OuZIUjXb5Pf9vgWpqo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=E8Pv08Ca; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=DsdqLgsQ; arc=none smtp.client-ip=205.220.180.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="E8Pv08Ca"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="DsdqLgsQ" Received: from pps.filterd (m0279868.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 60THLvTZ3914272 for ; Thu, 29 Jan 2026 20:25:12 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= TIyWfuFKG9M3pO5hQmbVZSaW8RBimd7V3pBdTPjwJ6A=; b=E8Pv08Ca/oUQS9hB ZCNVdyUPaPmHAb0tMd7umdEzkgtxTGSdyG1uqAi43M6r2rSBv/lE44S0NvIsO7mG ht4+V1T+H/jRPH5MqvDVwwFkGaOQVpNkNHxuLukDN6ZsJ8bys/HeO0Jd8pkefF7I XwCMLPB8VHsjr5MQg1QSYDdb8IGe08ZHn2kMq402lNbe+MiVsjM244MMOqCY6uZc S0cpcWEsw0L3xJq7fGO2PoCFkExVUb5oP2J4cMkd5Xa0GOQuhvEEaUy3t/7n3b6C dsKPWTBc8HOSEm4By3h5FB25ZvI8zcoTLiZufLbAStS6YiK/ohLGtUgqicyQZ/L+ /T4x1g== Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4c0bvvgjt8-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Thu, 29 Jan 2026 20:25:11 +0000 (GMT) Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-8c71655aa11so424910785a.3 for ; Thu, 29 Jan 2026 12:25:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1769718311; x=1770323111; darn=vger.kernel.org; h=in-reply-to:references:to:cc:subject:from:message-id:date :content-transfer-encoding:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=TIyWfuFKG9M3pO5hQmbVZSaW8RBimd7V3pBdTPjwJ6A=; b=DsdqLgsQ1P/J/X7q+4yjQQX7wT5NRr84qYnnrB78gfkCqyXgVv8wDydWYLDtovvpo7 XleXsM5PS/YGgDfDIQo9RCuzFXuTndB86wDg7+xxV4izn4ZX417JckugsiGSDCrDG4E+ mtCG98P9EEFWzGHNJivanWzKc6tqjpI3926q7XYT/IAFphFs2RZjpdalrkeL0/78sXSr zgFksIJNcAKfzUxU9DRO8g8z6KoyjZEY3yfvPR1fs1QPYW6tLel2BO+q32LUw5TH3T3Y NYpkYyvaggdsWIJvJEtLzUrzeHOjDUNzIwYFPlgp51gGmkO45p0r4IegkbCSxObjc4js +nkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769718311; x=1770323111; h=in-reply-to:references:to:cc:subject:from:message-id:date :content-transfer-encoding:mime-version:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=TIyWfuFKG9M3pO5hQmbVZSaW8RBimd7V3pBdTPjwJ6A=; b=erKAYf5owDcL3LrXxqzEg9hmhYbVfn3m6WMkPyb1zFKFGMl80Jt/jI9O2vX1CBWmHp CQPNz4RCxRLi6AG9UHejLifmBkEiqOxPWdk9MJCSKFq0EuWetuB03oqS5CL9z73Ad+Wa PG2et/UtSItGfhj80mqqWMVUbKEMzimrwiZVd5i3lH7KDorngIPtH2Gk1oqbO7u+4o5r 6ijYpQxwIMqBQfGiJcRrk98cb7JfwbXbGTzl8Z/b3RcOlKPtj3CemzTmTL9mlsLBuXJU MZ7T6c92VLp2lA2sWwuhYN192keY6Xn43C1Led2ZNqxnA7U0Y2Bf3NdSbZdKoPKk9N/I +q0w== X-Forwarded-Encrypted: i=1; AJvYcCWl09iQRu/4xiclqGIb0BWAPGV4MvG2VHn118BFzNISbBPDKNZ8YpwHmNCPFc9zZwLtNOHUSZvWk10=@vger.kernel.org X-Gm-Message-State: AOJu0YzI+N/lPmE9UUQ6oqlHv7jPxQbfhCnm3QLSUJ17EootvpEmlq+b z41Qk0IxiVd/8jlBQrA6K+qFUXB45AWd92MzmlPzjujM78YRaQQZDyNUNGQhl7mBUGXXi1RZuor 5yBKlRHS9Goqr0NxpiCmCVPraCeLf/PILCZ4xvPEi/Kj62Jor+1vqzEHGHiHS2OE= X-Gm-Gg: AZuq6aJecLv/6CGDlwxdXKjiFG5lbuy4VAj/iHLjD3fUlduM4qWkSPzk+Gvhf/Vvsqg cDgRCAwBWg8Ke7v22Gu6iDKA6gsxBPmBdFhtUJZwP8ljMVMYWttzFdb90D+suA7DpmPk6Pjr8Yj 6l8YWm2GYiCo2BxW/7L8guRMT46PYpsOVaX6s8+sBHLIyss99x1stnKo5PiuTG0YcbRG06BBGjk xVEv2ycvQRVpwKDzB7M3CRnteNMlGVr4AiBpFTdDc2DX7flzFlAckpSj63TB9Us1YkwJ6WX7AxB P1ZvTEB7c0DQOYire2tPoFCIDJJ4xa3Wj8Xyv8CZZPpviWBhaQiwtzxd3SytcNcLizR8jcUqrjb 3XcaO4mskl4Ir8JnmA+zQQVjdO7fr+w8QmcBcRFSybnX/MYQW X-Received: by 2002:a05:620a:29d2:b0:8c5:36be:41fe with SMTP id af79cd13be357-8c9eb32be89mr118653285a.60.1769718311169; Thu, 29 Jan 2026 12:25:11 -0800 (PST) X-Received: by 2002:a05:620a:29d2:b0:8c5:36be:41fe with SMTP id af79cd13be357-8c9eb32be89mr118650785a.60.1769718310701; Thu, 29 Jan 2026 12:25:10 -0800 (PST) Received: from localhost (ip-86-49-253-11.bb.vodafone.cz. [86.49.253.11]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4806ce4c3c6sm150902865e9.10.2026.01.29.12.25.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Jan 2026 12:25:10 -0800 (PST) Precedence: bulk X-Mailing-List: linux-doc@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 Date: Thu, 29 Jan 2026 20:25:08 +0000 Message-Id: From: =?utf-8?q?Radim_Kr=C4=8Dm=C3=A1=C5=99?= Subject: [SUGGESTION] KVM: RISC-V: detect gstage mode hierarchy Cc: , , , , , , , , , , , , , , , To: References: <20260125150450.27068-1-fangyu.yu@linux.alibaba.com> <20260125150450.27068-2-fangyu.yu@linux.alibaba.com> In-Reply-To: X-Authority-Analysis: v=2.4 cv=ZdEQ98VA c=1 sm=1 tr=0 ts=697bc227 cx=c_pps a=HLyN3IcIa5EE8TELMZ618Q==:117 a=HFCiZzTCIv7qJCpyeE1rag==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=M51BFTxLslgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=EUspDBNiAAAA:8 a=B30jFbksMaAZlFPmlSQA:9 a=QEXdDO2ut3YA:10 a=bTQJ7kPSJx9SKPbeHEYW:22 X-Proofpoint-GUID: XUkm-8bWL2RFQGuG0r0qtu2CJ4lgyKhN X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTI5MDE0NyBTYWx0ZWRfX6J4TAM323pUn HC7X2MJyauWimLtLDyyr1C44joR3ha47z+7JCWvBoN6qIeA/JQxYKRHQtpKFN/71s/G0FTGIhAp MYlu641/ERnDbioMUTZhB0JmUiFaJNWT/F2iX+6FJnhdGOtecYxqRap8GCgN5ahpIxyuv68aYd6 KZ2FaXk9afsq6nhY+S+Poh1fL7vcuKiNg1UR4JYGAlRTvRzijO67DXMXbp7y0cLLk3IHj7qqKVF rub6/ajcj5JWC19RocFpNlnYPdX/akK89mvf3VfYJ3cbxrj7TaeJRt7wq9/PCNhWMdj3zurPzai KK0ls72D/BqDDC13v6luVjoZvWT1vI6A1MMI32mliKleecVb6RzwRFgvGmcWRA+0+ZOFL3dJONu +lzLhZ/ftXeLiB6f+lTMIDORmg5tn47H8vt2CAz/c5Wq3nBU8bf01RaAYAMpzBaq5DrsoJR7IHT qaWGdvhddx21Ey2Ne2Q== X-Proofpoint-ORIG-GUID: XUkm-8bWL2RFQGuG0r0qtu2CJ4lgyKhN X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-01-29_03,2026-01-29_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 phishscore=0 spamscore=0 suspectscore=0 malwarescore=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2601290147 2026-01-29T15:27:35+00:00, Radim Kr=C4=8Dm=C3=A1=C5=99 : > (I'll reply with a patch later.) Something like this would avoid a bit of technical debt. The solution could be even more generic by returning a bitmap of supported modes, but that would be larger refactoring... Feel free to use it in the series, but beware: only compile-tested. It's late and hope it at least boots. :) Thanks. ---8<--- RISC-V ISA does not require a hierarchy of standard hgatp mode (i.e. 57x4 does not depend on 48x4 onr 39x4), yet future patches want to assume that the hierarchy exists, for simplicity. Only accept a hgatp mode if all narrower modes are supported as well. All sensible RISC-V implementations should have the hierarchy, since it's very cheap to add the narrower modes. Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 --- The hunk that removes the default values at the beginning of gstage.c should have been a separate patch, sorry. --- arch/riscv/include/asm/kvm_gstage.h | 2 +- arch/riscv/kvm/gstage.c | 66 ++++++++++++----------------- arch/riscv/kvm/main.c | 6 ++- 3 files changed, 32 insertions(+), 42 deletions(-) diff --git a/arch/riscv/include/asm/kvm_gstage.h b/arch/riscv/include/asm/k= vm_gstage.h index 595e2183173e..18db474ce583 100644 --- a/arch/riscv/include/asm/kvm_gstage.h +++ b/arch/riscv/include/asm/kvm_gstage.h @@ -67,6 +67,6 @@ void kvm_riscv_gstage_unmap_range(struct kvm_gstage *gsta= ge, =20 void kvm_riscv_gstage_wp_range(struct kvm_gstage *gstage, gpa_t start, gpa= _t end); =20 -void kvm_riscv_gstage_mode_detect(void); +unsigned long kvm_riscv_gstage_mode_detect(void); =20 #endif diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c index b67d60d722c2..678b304553bc 100644 --- a/arch/riscv/kvm/gstage.c +++ b/arch/riscv/kvm/gstage.c @@ -11,13 +11,8 @@ #include #include =20 -#ifdef CONFIG_64BIT -unsigned long kvm_riscv_gstage_mode __ro_after_init =3D HGATP_MODE_SV39X4; -unsigned long kvm_riscv_gstage_pgd_levels __ro_after_init =3D 3; -#else -unsigned long kvm_riscv_gstage_mode __ro_after_init =3D HGATP_MODE_SV32X4; -unsigned long kvm_riscv_gstage_pgd_levels __ro_after_init =3D 2; -#endif +unsigned long kvm_riscv_gstage_mode __ro_after_init; +unsigned long kvm_riscv_gstage_pgd_levels __ro_after_init; =20 #define gstage_pte_leaf(__ptep) \ (pte_val(*(__ptep)) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)) @@ -313,47 +308,38 @@ void kvm_riscv_gstage_wp_range(struct kvm_gstage *gst= age, gpa_t start, gpa_t end } } =20 -void __init kvm_riscv_gstage_mode_detect(void) +static inline unsigned long __init __kvm_riscv_gstage_mode_detect(void) { #ifdef CONFIG_64BIT - /* Try Sv57x4 G-stage mode */ - csr_write(CSR_HGATP, HGATP_MODE_SV57X4 << HGATP_MODE_SHIFT); - if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) =3D=3D HGATP_MODE_SV57X4) { - kvm_riscv_gstage_mode =3D HGATP_MODE_SV57X4; - kvm_riscv_gstage_pgd_levels =3D 5; - goto done; - } - - /* Try Sv48x4 G-stage mode */ - csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT); - if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) =3D=3D HGATP_MODE_SV48X4) { - kvm_riscv_gstage_mode =3D HGATP_MODE_SV48X4; - kvm_riscv_gstage_pgd_levels =3D 4; - goto done; - } - - /* Try Sv39x4 G-stage mode */ csr_write(CSR_HGATP, HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT); - if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) =3D=3D HGATP_MODE_SV39X4) { - kvm_riscv_gstage_mode =3D HGATP_MODE_SV39X4; - kvm_riscv_gstage_pgd_levels =3D 3; - goto done; - } + if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) !=3D HGATP_MODE_SV39X4) + return HGATP_MODE_OFF; + + csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT); + if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) !=3D HGATP_MODE_SV48X4) + return HGATP_MODE_SV39X4; + + csr_write(CSR_HGATP, HGATP_MODE_SV57X4 << HGATP_MODE_SHIFT); + if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) !=3D HGATP_MODE_SV57X4) + return HGATP_MODE_SV48X4; + + return HGATP_MODE_SV57X4; #else /* CONFIG_32BIT */ - /* Try Sv32x4 G-stage mode */ csr_write(CSR_HGATP, HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT); - if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) =3D=3D HGATP_MODE_SV32X4) { - kvm_riscv_gstage_mode =3D HGATP_MODE_SV32X4; - kvm_riscv_gstage_pgd_levels =3D 2; - goto done; - } + if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) !=3D HGATP_MODE_SV32X4) + return HGATP_MODE_OFF; + + return HGATP_MODE_SV32X4; #endif +} =20 - /* KVM depends on !HGATP_MODE_OFF */ - kvm_riscv_gstage_mode =3D HGATP_MODE_OFF; - kvm_riscv_gstage_pgd_levels =3D 0; +/* We could probably omit the HGATP write and fence. */ +unsigned long __init kvm_riscv_gstage_mode_detect(void) +{ + unsigned long gstage_mode =3D __kvm_riscv_gstage_mode_detect(); =20 -done: csr_write(CSR_HGATP, 0); kvm_riscv_local_hfence_gvma_all(); + + return gstage_mode; } diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c index 45536af521f0..58fd6ae8e04a 100644 --- a/arch/riscv/kvm/main.c +++ b/arch/riscv/kvm/main.c @@ -104,19 +104,23 @@ static int __init riscv_kvm_init(void) if (rc && rc !=3D -ENODEV) return rc; =20 - kvm_riscv_gstage_mode_detect(); + kvm_riscv_gstage_mode =3D kvm_riscv_gstage_mode_detect(); switch (kvm_riscv_gstage_mode) { case HGATP_MODE_SV32X4: str =3D "Sv32x4"; + kvm_riscv_gstage_pgd_levels =3D 2; break; case HGATP_MODE_SV39X4: str =3D "Sv39x4"; + kvm_riscv_gstage_pgd_levels =3D 3; break; case HGATP_MODE_SV48X4: str =3D "Sv48x4"; + kvm_riscv_gstage_pgd_levels =3D 4; break; case HGATP_MODE_SV57X4: str =3D "Sv57x4"; + kvm_riscv_gstage_pgd_levels =3D 5; break; default: kvm_riscv_nacl_exit(); --=20 2.51.0