From nobody Mon Feb 9 00:54:12 2026 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) (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 773D515ECCC; Wed, 4 Feb 2026 13:45:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.101 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770212728; cv=none; b=eqXQP/dgy4QaxScKmrQCpVY//3Uyymas9iigmrikRKq0ruR6cm7naQwpRyCjQ/KDG9JjDPlTBHAS9rhqfMnt0TLrhmGTNJ5XOcg/8YTysTOueHVKB2EpkU+SZNp2IsQx7f1EFKK8tN758FCBtUtHx9b0RljIZy4bYue9pnetpqo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770212728; c=relaxed/simple; bh=87LIlEktxosYN3tpXjpSdcBf0foNHMP4J/TIDkS36u8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CDD/r1+UHeiI8uWax+SjzqzOvrJXlQAZYo9dNYGJJJiifb1z1HQ16gDCnV0pxjJ+2qDsOawiLPxB0LiLwnpbvlJfxhedVzPHICfvtDwBSau3j17mb8waGZCoCrjmGtiROTKfJQwtyvCJl61woFkUTE0vucq0IpGAOl8JkR57yWM= 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=SuvUr+FR; arc=none smtp.client-ip=115.124.30.101 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="SuvUr+FR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1770212722; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=yciz5NKAtbksgmsOTnGqD+95AQXuV0o1EGcHqIl5HB4=; b=SuvUr+FRZSFWmBPtdpd+I/J2gt1dSzIJmqebiF+u/YO0mHJYIL8x4YHdmwQWARtFKEz1W7V6SXpjQ/ANugJ3mvGI1U32XGI3JggIsXCQrBztvaQIJf6gm+jUfLg2xJC3d1PcxgRWQAds3V+3MgFiAkzmnwqxVDBXgtunhaLymj0= Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0WyXBz9k_1770212719 cluster:ay36) by smtp.aliyun-inc.com; Wed, 04 Feb 2026 21:45:20 +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 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 v5 2/3] RISC-V: KVM: Detect and expose supported HGATP G-stage modes Date: Wed, 4 Feb 2026 21:45:06 +0800 Message-Id: <20260204134507.33912-3-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260204134507.33912-1-fangyu.yu@linux.alibaba.com> References: <20260204134507.33912-1-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 --- 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 b12605fbca44..76c37b5dc02d 100644 --- a/arch/riscv/include/asm/kvm_gstage.h +++ b/arch/riscv/include/asm/kvm_gstage.h @@ -30,6 +30,7 @@ struct kvm_gstage_mapping { #endif =20 extern unsigned long kvm_riscv_gstage_max_pgd_levels; +extern u32 kvm_riscv_gstage_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)) @@ -75,4 +76,14 @@ void kvm_riscv_gstage_wp_range(struct kvm_gstage *gstage= , gpa_t start, gpa_t end =20 void kvm_riscv_gstage_mode_detect(void); =20 +static inline u32 kvm_riscv_get_hgatp_mode_mask(void) +{ + return kvm_riscv_gstage_mode_mask; +} + +static inline bool kvm_riscv_hgatp_mode_is_valid(unsigned long mode) +{ + return kvm_riscv_gstage_mode_mask & BIT(mode); +} + #endif diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c index 2d0045f502d1..328d4138f162 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_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_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_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_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_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_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