From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 609462F0C5C; Mon, 22 Sep 2025 19:44:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758570254; cv=none; b=RLmOms95eiwE0B3uJhlv6PKJaWJN7zfelWiHWbGCyEcmjtmJhlmhozSSRhngVzDjXz8YkOW6BCzpkIxjVHlkQc2FcIVdSwDgRc/vuqFWIGxaq/qdIRIGvMcmCfK4Iz7avKysYfYBYsh5ruaRgmMPJRagDtgygw450RcC4rvMvpc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758570254; c=relaxed/simple; bh=/kn5cfA+gDwjgiImUxJWomrG0AElGgZV7+L7wsxTHRo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cPkHGUWRu4xpzGTCUir4KtjVERqvZdS33ftj87VvkCO5iAINsPNTz5O3YWw29JmxGecK+Vap3Lqo83oOnIdAV+4UIqndfj+BDh87h2obVvmZR5GYenSyTXVbYRW+D9gOUzZrnthaWWd4/tepKFdDB22DCg08UgdnuIoh65Wg9uQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eaksCnbu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eaksCnbu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC840C4CEF0; Mon, 22 Sep 2025 19:44:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1758570254; bh=/kn5cfA+gDwjgiImUxJWomrG0AElGgZV7+L7wsxTHRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eaksCnbuI3d1VH69ZoluSfc12nFawqyG3yqBp4fpouXtbTg8bi0qdyLUmeH0NqXQQ Ovb9JC5Zqxx4B2q5ZAsjZmJKahrMxPCaXLwLhM/uPvongEi5T2ifi8FeOcL4ZIieDM RLIIJtV6fpypHdn4hREXxOR4zOIY5++ecJX+QCu4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bibo Mao , Huacai Chen Subject: [PATCH 6.16 077/149] LoongArch: KVM: Fix VM migration failure with PTW enabled Date: Mon, 22 Sep 2025 21:29:37 +0200 Message-ID: <20250922192414.827196616@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250922192412.885919229@linuxfoundation.org> References: <20250922192412.885919229@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bibo Mao commit f58c9aa1065f73d243904b267c71f6a9d1e9f90e upstream. With PTW disabled system, bit _PAGE_DIRTY is a HW bit for page writing. However with PTW enabled system, bit _PAGE_WRITE is also a "HW bit" for page writing, because hardware synchronizes _PAGE_WRITE to _PAGE_DIRTY automatically. Previously, _PAGE_WRITE is treated as a SW bit to record the page writeable attribute for the fast page fault handling in the secondary MMU, however with PTW enabled machine, this bit is used by HW already (so setting it will silence the TLB modify exception). Here define KVM_PAGE_WRITEABLE with the SW bit _PAGE_MODIFIED, so that it can work on both PTW disabled and enabled machines. And for HW write bits, both _PAGE_DIRTY and _PAGE_WRITE are set or clear together. Cc: stable@vger.kernel.org Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman --- arch/loongarch/include/asm/kvm_mmu.h | 20 ++++++++++++++++---- arch/loongarch/kvm/mmu.c | 8 ++++---- 2 files changed, 20 insertions(+), 8 deletions(-) --- a/arch/loongarch/include/asm/kvm_mmu.h +++ b/arch/loongarch/include/asm/kvm_mmu.h @@ -16,6 +16,13 @@ */ #define KVM_MMU_CACHE_MIN_PAGES (CONFIG_PGTABLE_LEVELS - 1) +/* + * _PAGE_MODIFIED is a SW pte bit, it records page ever written on host + * kernel, on secondary MMU it records the page writeable attribute, in + * order for fast path handling. + */ +#define KVM_PAGE_WRITEABLE _PAGE_MODIFIED + #define _KVM_FLUSH_PGTABLE 0x1 #define _KVM_HAS_PGMASK 0x2 #define kvm_pfn_pte(pfn, prot) (((pfn) << PFN_PTE_SHIFT) | pgprot_val(prot)) @@ -52,10 +59,10 @@ static inline void kvm_set_pte(kvm_pte_t WRITE_ONCE(*ptep, val); } -static inline int kvm_pte_write(kvm_pte_t pte) { return pte & _PAGE_WRITE; } -static inline int kvm_pte_dirty(kvm_pte_t pte) { return pte & _PAGE_DIRTY; } static inline int kvm_pte_young(kvm_pte_t pte) { return pte & _PAGE_ACCESSED; } static inline int kvm_pte_huge(kvm_pte_t pte) { return pte & _PAGE_HUGE; } +static inline int kvm_pte_dirty(kvm_pte_t pte) { return pte & __WRITEABLE; } +static inline int kvm_pte_writeable(kvm_pte_t pte) { return pte & KVM_PAGE_WRITEABLE; } static inline kvm_pte_t kvm_pte_mkyoung(kvm_pte_t pte) { @@ -69,12 +76,12 @@ static inline kvm_pte_t kvm_pte_mkold(kv static inline kvm_pte_t kvm_pte_mkdirty(kvm_pte_t pte) { - return pte | _PAGE_DIRTY; + return pte | __WRITEABLE; } static inline kvm_pte_t kvm_pte_mkclean(kvm_pte_t pte) { - return pte & ~_PAGE_DIRTY; + return pte & ~__WRITEABLE; } static inline kvm_pte_t kvm_pte_mkhuge(kvm_pte_t pte) @@ -87,6 +94,11 @@ static inline kvm_pte_t kvm_pte_mksmall( return pte & ~_PAGE_HUGE; } +static inline kvm_pte_t kvm_pte_mkwriteable(kvm_pte_t pte) +{ + return pte | KVM_PAGE_WRITEABLE; +} + static inline int kvm_need_flush(kvm_ptw_ctx *ctx) { return ctx->flag & _KVM_FLUSH_PGTABLE; --- a/arch/loongarch/kvm/mmu.c +++ b/arch/loongarch/kvm/mmu.c @@ -569,7 +569,7 @@ static int kvm_map_page_fast(struct kvm_ /* Track access to pages marked old */ new = kvm_pte_mkyoung(*ptep); if (write && !kvm_pte_dirty(new)) { - if (!kvm_pte_write(new)) { + if (!kvm_pte_writeable(new)) { ret = -EFAULT; goto out; } @@ -856,9 +856,9 @@ retry: prot_bits |= _CACHE_SUC; if (writeable) { - prot_bits |= _PAGE_WRITE; + prot_bits = kvm_pte_mkwriteable(prot_bits); if (write) - prot_bits |= __WRITEABLE; + prot_bits = kvm_pte_mkdirty(prot_bits); } /* Disable dirty logging on HugePages */ @@ -904,7 +904,7 @@ retry: kvm_release_faultin_page(kvm, page, false, writeable); spin_unlock(&kvm->mmu_lock); - if (prot_bits & _PAGE_DIRTY) + if (kvm_pte_dirty(prot_bits)) mark_page_dirty_in_slot(kvm, memslot, gfn); out: