From mboxrd@z Thu Jan 1 00:00:00 1970 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 534BB24BBF4; Thu, 2 Apr 2026 01:30:17 +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=1775093421; cv=none; b=LrM66hQ3Kv7SrZFX/4Ic3hpCdKHrDY7UO+79q6rQSdyLyEbR0ufHSaoe/ylHaPG172gL827Me8tL9nRFoGi6PzDWQhvkOBT7OK7bS2o0bI1D4F1hKMAxhM0hfyRFTyjGXb8zOkwptsozmT56cpbhPLBKIJBtgnymIHyOOUA2xwQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775093421; c=relaxed/simple; bh=NjmXATPGid77lEYSs73L1TeQKlGhYK8+n9RO1pStMpo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=LkkLUEuNyHa6kPk959usB1JMz6Oj9Tb/pbiVqLBytuLeLBXEQVfhxmvlOvHGUwo2aQcAhjRKcUnFFfG8j4jBuq8ukDC7cT7u+9PoTirIO2Ii1ZypafEz4Yezs/aAgT7MWRZd2HlZn7HfDpToNghZ8g8Q3330Qazh2nZAm1As8us= 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=yEGSW+7g; 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="yEGSW+7g" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1775093415; h=From:To:Subject:Date:Message-Id:MIME-Version:Content-Type; bh=LQI8bgcOyvJ94DrVUS67dvIGyB2c7fWfel9wByeq7fM=; b=yEGSW+7gU/q8FtO3BrF2/8I1db9PRn2cykK47MsqzrE8ERqbCE6kUkb5Y/h6D11kZ8RbO1YTPhnLqhiOqisEioC7kIzMJB1kldlNl8UuqXpPt4Faw1oCuZEWhLIwITQFNu84VE8fQs3FJsEJTKNCX58NfQsirVxERxH3tGB+7sg= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R271e4;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_---0X0FQ265_1775093412; Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0X0FQ265_1775093412 cluster:ay36) by smtp.aliyun-inc.com; Thu, 02 Apr 2026 09:30:13 +0800 From: fangyu.yu@linux.alibaba.com To: anup@brainfault.org Cc: alex@ghiti.fr, andrew.jones@oss.qualcomm.com, aou@eecs.berkeley.edu, atish.patra@linux.dev, corbet@lwn.net, fangyu.yu@linux.alibaba.com, guoren@kernel.org, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, palmer@dabbelt.com, pbonzini@redhat.com, pjw@kernel.org, radim.krcmar@oss.qualcomm.com, skhan@linuxfoundation.org Subject: Re: Re: [PATCH v6 3/4] RISC-V: KVM: Detect and expose supported HGATP G-stage modes Date: Thu, 2 Apr 2026 09:30:10 +0800 Message-Id: <20260402013010.9030-1-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit >> >> 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 >> --- >> 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/kvm_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 >> >> extern unsigned long kvm_riscv_gstage_max_pgd_levels; >> +extern u32 kvm_riscv_gstage_supported_mode_mask; >> >> #define kvm_riscv_gstage_pgd_xbits 2 >> #define kvm_riscv_gstage_pgd_size (1UL << (HGATP_PAGE_SHIFT + kvm_riscv_gstage_pgd_xbits)) >> @@ -102,4 +103,14 @@ static inline void kvm_riscv_gstage_init(struct kvm_gstage *gstage, struct kvm * >> gstage->pgd_levels = kvm->arch.pgd_levels; >> } >> >> +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 = 3; >> #else >> unsigned long kvm_riscv_gstage_max_pgd_levels __ro_after_init = 2; >> #endif >> +/* Bitmask of supported HGATP.MODE encodings (BIT(HGATP_MODE_*)). */ >> +u32 kvm_riscv_gstage_supported_mode_mask __ro_after_init; >> >> #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 *gstage, gpa_t start, gpa_t end >> } >> } >> >> +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) == mode); >> +} >> + >> void __init kvm_riscv_gstage_mode_detect(void) >> { >> + kvm_riscv_gstage_supported_mode_mask = 0; >> + kvm_riscv_gstage_max_pgd_levels = 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) == HGATP_MODE_SV57X4) { >> - kvm_riscv_gstage_max_pgd_levels = 5; >> - goto done; >> + /* Try Sv39x4 G-stage mode */ >> + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV39X4)) { >> + kvm_riscv_gstage_supported_mode_mask |= BIT(HGATP_MODE_SV39X4); >> + kvm_riscv_gstage_max_pgd_levels = 3; >> } >> >> /* Try Sv48x4 G-stage mode */ >> - csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT); >> - if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) { >> + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV48X4)) { >> + kvm_riscv_gstage_supported_mode_mask |= BIT(HGATP_MODE_SV48X4); >> kvm_riscv_gstage_max_pgd_levels = 4; >> - goto done; > >Keep the original approach until then NACK to this series. > Hi Anup, Thanks for the review. Ack. I’ll keep the original HGATP mode probing logic for now and send a v7 accordingly. Thanks, Fangyu >Regards, >Anup > >> } >> >> - /* Try Sv39x4 G-stage mode */ >> - csr_write(CSR_HGATP, HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT); >> - if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV39X4) { >> - kvm_riscv_gstage_max_pgd_levels = 3; >> - goto done; >> + /* Try Sv57x4 G-stage mode */ >> + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV57X4)) { >> + kvm_riscv_gstage_supported_mode_mask |= BIT(HGATP_MODE_SV57X4); >> + kvm_riscv_gstage_max_pgd_levels = 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) == HGATP_MODE_SV32X4) { >> + if (kvm_riscv_hgatp_mode_supported(HGATP_MODE_SV32X4)) { >> + kvm_riscv_gstage_supported_mode_mask |= BIT(HGATP_MODE_SV32X4); >> kvm_riscv_gstage_max_pgd_levels = 2; >> - goto done; >> } >> #endif >> >> - /* KVM depends on !HGATP_MODE_OFF */ >> - kvm_riscv_gstage_max_pgd_levels = 0; >> - >> -done: >> csr_write(CSR_HGATP, 0); >> kvm_riscv_local_hfence_gvma_all(); >> } >> -- >> 2.50.1 >>