From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 92F103815E8 for ; Wed, 1 Jul 2026 17:36:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782927363; cv=none; b=W5vniflBykSkjq+8iVoFkrs62H51jpLkINiBB4MU0Z6y4u427dCL5my0F71B6rG9Si9WbKEABXGhMwY6CwvSXEljjPhqxCKDwAVvstfcr+cxwHsREkzswLSfXYuaqt+BdoLAphXYbq8XJN5ZE3ri6RE7E6DIrQt4vk3ryUZOCRY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782927363; c=relaxed/simple; bh=tUVjgnoCXK425hJ9lnJj9A/8pGEa+OPuvDAnVXgMXvg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Je320jEzKPy0BkaqGO+aSq0FyxvUBg/WJTRWhXkeqpL6TZCl95S7YCr2dUPv+uWLA3evt+FQSXh6McnyTghSCuoiOxTCqu2/hLJLETzsWca3bYgPbzEeRntXOvyNZTzPqfbjJOxVCGodW0BoP/7KZipm5jPLbmrXNIx3iLQHT70= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=aYSfjKWg; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="aYSfjKWg" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 70A97455B; Wed, 1 Jul 2026 10:35:55 -0700 (PDT) Received: from thinkpad-e142931.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B4F103F85F; Wed, 1 Jul 2026 10:35:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1782927359; bh=tUVjgnoCXK425hJ9lnJj9A/8pGEa+OPuvDAnVXgMXvg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aYSfjKWghVCshUScZy3e0nWr9yRnuSNXSPRfOYH30kUO0/+sBa1dCNwsOpNToP5Zz 8p3tKf7Xv8D8o6goUBvUnvkdhaGYGUw46dhm/uHc0BY7dqPGLTrwzaE0vsRD95FGwN IJGlD4zOdj0BIEDEdThQ328NQSuocKvfVuor7SSw= Date: Wed, 1 Jul 2026 18:35:41 +0100 From: Wei-Lin Chang To: Leonardo Bras Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Itaru Kitayama , Sebastian Ene Subject: Re: [PATCH v2 6/6] KVM: arm64: ptdump: Introduce the shadow ptdump file Message-ID: References: <20260630121005.1130996-1-weilin.chang@arm.com> <20260630121005.1130996-7-weilin.chang@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jul 01, 2026 at 04:28:35PM +0100, Leonardo Bras wrote: > On Tue, Jun 30, 2026 at 01:10:05PM +0100, Wei-Lin Chang wrote: > > Create a ptdump file for all shadow page tables. It will dump out all > > valid shadow page tables at the time of request, with the mmu's index, > > guest VTCR_EL2, VTTBR_EL2, and whether the guest stage-2 is enabled or > > not. > > > > Also detach the nested mmu array under the mmu_lock in > > kvm_arch_flush_shadow_all() so readers cannot race with the array being > > removed, then free the old array after dropping the lock. > > Out of curiosity: why drop the lock before kfree'ing ? Because kvfree() can sleep! :) Thanks, Wei-Lin Chang > > Thanks! > Leo > > > > > Signed-off-by: Wei-Lin Chang > > --- > > arch/arm64/kvm/nested.c | 12 ++++++-- > > arch/arm64/kvm/ptdump.c | 61 ++++++++++++++++++++++++++++++++++++++++- > > 2 files changed, 69 insertions(+), 4 deletions(-) > > > > diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c > > index 6435efd65cb5..17a180ddf6ca 100644 > > --- a/arch/arm64/kvm/nested.c > > +++ b/arch/arm64/kvm/nested.c > > @@ -1283,6 +1283,7 @@ void kvm_nested_s2_flush(struct kvm *kvm) > > > > void kvm_arch_flush_shadow_all(struct kvm *kvm) > > { > > + struct kvm_s2_mmu *mmus; > > int i; > > > > for (i = 0; i < kvm->arch.nested_mmus_size; i++) { > > @@ -1291,9 +1292,14 @@ void kvm_arch_flush_shadow_all(struct kvm *kvm) > > if (!WARN_ON(atomic_read(&mmu->refcnt))) > > kvm_free_stage2_pgd(mmu); > > } > > - kvfree(kvm->arch.nested_mmus); > > - kvm->arch.nested_mmus = NULL; > > - kvm->arch.nested_mmus_size = 0; > > + > > + scoped_guard(write_lock, &kvm->mmu_lock) { > > + mmus = kvm->arch.nested_mmus; > > + kvm->arch.nested_mmus = NULL; > > + kvm->arch.nested_mmus_size = 0; > > + } > > + > > + kvfree(mmus); > > kvm_uninit_stage2_mmu(kvm); > > } > > > > diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c > > index 40f93b7c7ad9..1649eaa75798 100644 > > --- a/arch/arm64/kvm/ptdump.c > > +++ b/arch/arm64/kvm/ptdump.c > > @@ -181,6 +181,50 @@ static int kvm_ptdump_guest_canonical_show(struct seq_file *m, void *unused) > > return 0; > > } > > > > +static int kvm_ptdump_guest_nested_show(struct seq_file *m, void *unused) > > +{ > > + int ret = 0, i; > > + struct kvm_ptdump_guest_state *st = m->private; > > + struct kvm *kvm = st->kvm; > > + struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) { > > + .cb = kvm_ptdump_visitor, > > + .arg = &st->parser_state, > > + .flags = KVM_PGTABLE_WALK_LEAF, > > + }; > > + > > + guard(write_lock)(&kvm->mmu_lock); > > + > > + if (!kvm->arch.nested_mmus) > > + return 0; > > + > > + for (i = 0; i < kvm->arch.nested_mmus_size; i++) { > > + struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i]; > > + > > + if (!mmu->pgt) > > + continue; > > + > > + if (kvm_s2_mmu_valid(mmu)) { > > + memset(st, 0, sizeof(*st)); > > + ret = kvm_ptdump_parser_init(st, kvm, mmu->pgt); > > + if (ret) > > + return ret; > > + st->parser_state = (struct ptdump_pg_state) { > > + .marker = &st->ipa_marker[0], > > + .level = -1, > > + .pg_level = &st->level[0], > > + .seq = m, > > + }; > > + seq_printf(m, "nested mmu %d VTCR: 0x%016llx VTTBR: 0x%016llx s2: %s\n", > > + i, mmu->tlb_vtcr, mmu->tlb_vttbr, > > + mmu->nested_stage2_enabled ? "enabled" : "disabled"); > > + ret = kvm_pgtable_walk(mmu->pgt, 0, BIT(mmu->pgt->ia_bits), &walker); > > + if (ret) > > + return ret; > > + } > > + } > > + return ret; > > +} > > + > > static int kvm_ptdump_guest_open(struct inode *m, struct file *file, > > int (*show)(struct seq_file *, void *)) > > { > > @@ -212,6 +256,11 @@ static int kvm_ptdump_guest_canonical_open(struct inode *m, struct file *file) > > return kvm_ptdump_guest_open(m, file, kvm_ptdump_guest_canonical_show); > > } > > > > +static int kvm_ptdump_guest_nested_open(struct inode *m, struct file *file) > > +{ > > + return kvm_ptdump_guest_open(m, file, kvm_ptdump_guest_nested_show); > > +} > > + > > static int kvm_ptdump_guest_close(struct inode *m, struct file *file) > > { > > struct kvm *kvm = m->i_private; > > @@ -230,6 +279,13 @@ static const struct file_operations kvm_ptdump_guest_canonical_fops = { > > .release = kvm_ptdump_guest_close, > > }; > > > > +static const struct file_operations kvm_ptdump_guest_nested_fops = { > > + .open = kvm_ptdump_guest_nested_open, > > + .read = seq_read, > > + .llseek = seq_lseek, > > + .release = kvm_ptdump_guest_close, > > +}; > > + > > static int kvm_pgtable_range_show(struct seq_file *m, void *unused) > > { > > struct kvm *kvm = m->private; > > @@ -307,6 +363,9 @@ void kvm_s2_ptdump_create_debugfs(struct kvm *kvm) > > kvm, &kvm_pgtable_range_fops); > > debugfs_create_file("stage2_levels", 0400, kvm->debugfs_dentry, > > kvm, &kvm_pgtable_levels_fops); > > - if (cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) > > + if (cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) { > > kvm->arch.debugfs_nv_dentry = debugfs_create_dir("nested", kvm->debugfs_dentry); > > + debugfs_create_file("shadow_page_tables", 0400, kvm->arch.debugfs_nv_dentry, > > + kvm, &kvm_ptdump_guest_nested_fops); > > + } > > } > > -- > > 2.43.0 > >