From nobody Thu Apr 2 06:10:00 2026 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) (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 1521F37CD57; Mon, 30 Mar 2026 12:26:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.110 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774873597; cv=none; b=a6NEoNA8fPL3rmULtJj4TtfQ+9fLjzLlW1gp3daCKG9Gm+NiXtsQbVeq2SjNIznQkrryN8fvUprAR3Ow7MX+5085VCl8hZkujblWCQ1oKsDJmXyX9UGm3/AQw8IYDybn37X7sJ1Evtz/bdwWVrhkvCEiCn/cTa1CE5hmsqVg4q8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774873597; c=relaxed/simple; bh=Xn/WZtZyMpPye9m8abp212wYw38KSOoY3nIsJV0J4GM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=JojDiDFyvSEUjGM8vaGRz8JghZGX+recLLM2FkCJcLQ22rEUJc5ULtPmUBLoB33ncZPJYNYCo8HqHS4efUyy91vgdvu2ZNgy/UjTJRNiTpa5NOLlCf5ZLqbkzt6AHrmrQnqMm0eAuRxyt55C4iTLw/iRmiKfjiz5z/jkmd8NQhI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=Jfzrhjxl; arc=none smtp.client-ip=115.124.30.110 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="Jfzrhjxl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1774873593; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=PT+yx01BbG86omMromavfHwf6ELYE5YcV+gpW/gZMbk=; b=Jfzrhjxl6h90Y2n4R7N8OpzN2M8yrMIIEFmfAby5Ur791EvlDJZelFZZRY5VABVQsr83GXDbFhtWDQ4QyXOpKWWCtwzeGCu9krIVpBVas8Vg/LGzDv7erhOYZHPMW07zUfjdiNCZyFnpxYtiPxfZVXjhgsueBwpG2BtklrFWyc8= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam011083073210;MF=fangyu.yu@linux.alibaba.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---0X.zfcJ9_1774873591; Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0X.zfcJ9_1774873591 cluster:ay36) by smtp.aliyun-inc.com; Mon, 30 Mar 2026 20:26:32 +0800 From: fangyu.yu@linux.alibaba.com To: pbonzini@redhat.com, corbet@lwn.net, anup@brainfault.org, atish.patra@linux.dev, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, skhan@linuxfoundation.org Cc: guoren@kernel.org, radim.krcmar@oss.qualcomm.com, andrew.jones@oss.qualcomm.com, linux-doc@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Fangyu Yu Subject: [PATCH v6 3/4] RISC-V: KVM: Detect and expose supported HGATP G-stage modes Date: Mon, 30 Mar 2026 20:26:00 +0800 Message-Id: <20260330122601.22140-4-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260330122601.22140-1-fangyu.yu@linux.alibaba.com> References: <20260330122601.22140-1-fangyu.yu@linux.alibaba.com> 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" From: Fangyu Yu Extend kvm_riscv_gstage_mode_detect() to probe all HGATP.MODE values supported by the host and record them in a bitmask. Keep tracking the maximum supported G-stage page table level for existing internal users. Also provide lightweight helpers to retrieve the supported-mode bitmask and validate a requested HGATP.MODE against it. Signed-off-by: Fangyu Yu Reviewed-by: Andrew Jones Reviewed-by: Guo Ren --- arch/riscv/include/asm/kvm_gstage.h | 11 ++++++++ arch/riscv/kvm/gstage.c | 43 +++++++++++++++-------------- 2 files changed, 34 insertions(+), 20 deletions(-) diff --git a/arch/riscv/include/asm/kvm_gstage.h b/arch/riscv/include/asm/k= vm_gstage.h index 70d9d483365e..bbf8f45c6563 100644 --- a/arch/riscv/include/asm/kvm_gstage.h +++ b/arch/riscv/include/asm/kvm_gstage.h @@ -31,6 +31,7 @@ struct kvm_gstage_mapping { #endif =20 extern unsigned long kvm_riscv_gstage_max_pgd_levels; +extern u32 kvm_riscv_gstage_supported_mode_mask; =20 #define kvm_riscv_gstage_pgd_xbits 2 #define kvm_riscv_gstage_pgd_size (1UL << (HGATP_PAGE_SHIFT + kvm_riscv_gs= tage_pgd_xbits)) @@ -102,4 +103,14 @@ static inline void kvm_riscv_gstage_init(struct kvm_gs= tage *gstage, struct kvm * gstage->pgd_levels =3D kvm->arch.pgd_levels; } =20 +static inline u32 kvm_riscv_get_hgatp_mode_mask(void) +{ + return kvm_riscv_gstage_supported_mode_mask; +} + +static inline bool kvm_riscv_hgatp_mode_is_valid(unsigned long mode) +{ + return kvm_riscv_gstage_supported_mode_mask & BIT(mode); +} + #endif diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c index 7c4c34bc191b..459041255c14 100644 --- a/arch/riscv/kvm/gstage.c +++ b/arch/riscv/kvm/gstage.c @@ -16,6 +16,8 @@ unsigned long kvm_riscv_gstage_max_pgd_levels __ro_after_= init =3D 3; #else unsigned long kvm_riscv_gstage_max_pgd_levels __ro_after_init =3D 2; #endif +/* Bitmask of supported HGATP.MODE encodings (BIT(HGATP_MODE_*)). */ +u32 kvm_riscv_gstage_supported_mode_mask __ro_after_init; =20 #define gstage_pte_leaf(__ptep) \ (pte_val(*(__ptep)) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)) @@ -315,42 +317,43 @@ void kvm_riscv_gstage_wp_range(struct kvm_gstage *gst= age, gpa_t start, gpa_t end } } =20 +static bool __init kvm_riscv_hgatp_mode_supported(unsigned long mode) +{ + csr_write(CSR_HGATP, mode << HGATP_MODE_SHIFT); + return ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) =3D=3D mode); +} + void __init kvm_riscv_gstage_mode_detect(void) { + kvm_riscv_gstage_supported_mode_mask =3D 0; + kvm_riscv_gstage_max_pgd_levels =3D 0; + #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_max_pgd_levels =3D 5; - goto done; + /* Try Sv39x4 G-stage mode */ + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV39X4)) { + kvm_riscv_gstage_supported_mode_mask |=3D BIT(HGATP_MODE_SV39X4); + kvm_riscv_gstage_max_pgd_levels =3D 3; } =20 /* 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) { + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV48X4)) { + kvm_riscv_gstage_supported_mode_mask |=3D BIT(HGATP_MODE_SV48X4); kvm_riscv_gstage_max_pgd_levels =3D 4; - goto done; } =20 - /* 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_max_pgd_levels =3D 3; - goto done; + /* Try Sv57x4 G-stage mode */ + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV57X4)) { + kvm_riscv_gstage_supported_mode_mask |=3D BIT(HGATP_MODE_SV57X4); + kvm_riscv_gstage_max_pgd_levels =3D 5; } #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) { + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV32X4)) { + kvm_riscv_gstage_supported_mode_mask |=3D BIT(HGATP_MODE_SV32X4); kvm_riscv_gstage_max_pgd_levels =3D 2; - goto done; } #endif =20 - /* KVM depends on !HGATP_MODE_OFF */ - kvm_riscv_gstage_max_pgd_levels =3D 0; - -done: csr_write(CSR_HGATP, 0); kvm_riscv_local_hfence_gvma_all(); } --=20 2.50.1