From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 60609368299 for ; Fri, 31 Jul 2026 15:03:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785510189; cv=none; b=GIBVS1ulSDC1hiDcerJ7GDyCMKe43OnWQ4zuXqY6XJwnSf5H3SWjVOr6UafUUVMoPNyqzoOBMRnq36laQ1lvPWho24kc3+wUv8w4hnPSDPWb+uhAtyeoQnq7ktN2uzlg6IMZ9HHUgH1e6z/U8SefqQRqWuf0tqAXWy3MXTFzFlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785510189; c=relaxed/simple; bh=wkeBixyhVNYNVDFbkNkDflDqhinWDKQBwQ7Z5bePJRs=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=mejodv2Yd7Ozu8mlSt3APrEn70Lo0f4YoZbrWY2QzixgGf5x4/dtkWH53iZ4Sp7oW3GaHQaXxbZc02wPnIQODpH1B3FSCKNdmaE/S4SLtLIJOVUgdfxu0i8AXDOX2IQZRS9Gu/b6C68+zJRygKIucE31V5cV2Cwb+rYVh1x6Bo8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oM/IIsDR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oM/IIsDR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB95E1F000E9; Fri, 31 Jul 2026 15:03:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785510187; bh=drRJG6ds69O9LwV6v3ykfptHYlXD3AOi/zrzDj3LKBI=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=oM/IIsDRo9DntuOBBXMJuP+Gus4ClkO6nBSlBGa38RdeIvDU6ZfQWIbqH0tD5hpAq gMDfbJVvAe6lFJe7yUNUDdKcUBCQtD+LlHzc6RD4K75ULEfM+Mr+5FGMjg8j/wu8iF 0Fhe1vyR7YJj4PKkpWI8vV5S44dEEd5+NVcrNIIzC7fCklFFJqGy93QIelxxvyKVhQ rrxxF0YarU2zwx/1+uS4HUVUYDzFeDqAfHLOfHLVvFnOiD0fryqyMs0e68mf0rtBO9 Rdc0aV3KlFuoq5TmFuFS9Bko73ymeoltcE4jkByYp9JNuobm4txzi96/0xEIXR2fgh qOQoQ5iclUD6w== From: sashiko-bot@kernel.org Subject: Re: [PATCH v4 09/17] KVM: arm64: Add selftests for the pKVM heap allocator Reply-To: sashiko-reviews@lists.linux.dev To: "Vincent Donnefort" Cc: "Oliver Upton" , "Marc Zyngier" , kvmarm@lists.linux.dev In-Reply-To: <20260731143541.956291-10-vdonnefort@google.com> References: <20260731143541.956291-1-vdonnefort@google.com> <20260731143541.956291-10-vdonnefort@google.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 31 Jul 2026 15:03:07 +0000 Message-Id: <20260731150307.AB95E1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 3 potential issue(= s) to consider: - [High] The pKVM hyp allocator fails to map backing memory for chunks appe= nded to a previous chunk that does not explicitly track the unmapped bounda= ry, leading to a fatal EL2 data abort. - [Medium] The `__pkvm_hyp_alloc_selftest` hypercall is placed in the alway= s-on band instead of the init-only band, violating hypervisor lifecycle rul= es. - [Medium] Physical pages temporarily held in the local `host_mc` memcache = are permanently leaked if an assertion fails during the selftest. -- --- Patch [9]: [PATCH v4 09/17] KVM: arm64: Add selftests for the pKVM heap= allocator --- commit 68a0bf1c1fb29e6fed5c0a59e15840d4a948bd3e Author: Vincent Donnefort KVM: arm64: Add selftests for the pKVM heap allocator Introduce a comprehensive runtime selftest for the pKVM hypervisor heap allocator, executed during init when CONFIG_NVHE_EL2_DEBUG is enabled. > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kv= m_asm.h > index 0c3126179704f..08466f608d1f5 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -92,6 +92,7 @@ enum __kvm_host_smccc_func { > __KVM_HOST_SMCCC_FUNC___pkvm_hyp_topup, > __KVM_HOST_SMCCC_FUNC___pkvm_hyp_reclaim, > __KVM_HOST_SMCCC_FUNC___pkvm_hyp_reclaimable, > + __KVM_HOST_SMCCC_FUNC___pkvm_hyp_alloc_selftest, > =20 > MARKER(__KVM_HOST_SMCCC_FUNC_PKVM_ONLY), [Severity: Medium] Is __pkvm_hyp_alloc_selftest placed in the correct hypercall ID band here? Placing it before the PKVM_ONLY marker puts the hypercall in the always-on band rather than the init-only band. Since this is an initialization test meant to run before pKVM finalization, should it be placed in the init-only band to ensure it is not exposed to the untrusted host kernel post-deprivilege? [ ... ] > diff --git a/arch/arm64/kvm/hyp/nvhe/alloc.c b/arch/arm64/kvm/hyp/nvhe/al= loc.c > index af4ab53784f7f..de636fdf976bf 100644 > --- a/arch/arm64/kvm/hyp/nvhe/alloc.c > +++ b/arch/arm64/kvm/hyp/nvhe/alloc.c [ ... ] > + /* Test reclaiming */ > + if (addr1 !=3D selftest_alloc(0)) > + return -EINVAL; > + if (addr2 !=3D selftest_alloc(PAGE_SIZE * 2)) > + return -EINVAL; > + addr3 =3D selftest_alloc(0); > + addr4 =3D selftest_alloc(PAGE_SIZE); [Severity: High] Does allocating addr4 here trigger a data abort due to unmapped memory? When appending a new chunk, hyp_allocator_map() uses chunk_unmapped(prev) to find the unmapped boundary. If the previous chunk (addr3) does not track it (which occurs when the boundary is held by an earlier chunk), it returns 0 and skips mapping. Because addr4 is allocated after addr3, it crosses the actual unmapped boundary without mapping new pages. This leaves the new region unmapped, which leads to a fatal EL2 data abort when the hypervisor initializes and accesses the memory. [ ... ] > + > + /* Test punching a hole in the middle of a free chunk ... */ > + selftest_free(addr2); > + hyp_allocator_reclaim(allocator, &host_mc, SELFTEST_MAX_PAGES); > + if (host_mc.nr_pages !=3D SELFTEST_MAX_PAGES - 2) > + return -EINVAL; > + > + if (selftest_alloc(PAGE_SIZE)) > + return -EINVAL; > + if (selftest_errno() !=3D -ENOMEM) > + return -EINVAL; [Severity: Medium] Do these error paths leak the physical pages currently held in host_mc? The hyp_allocator_selftest() function temporarily stores reclaimed physical pages in the local host_mc memcache stack variable. If any of these subsequent assertions fail, the function returns -EINVAL directly without draining host_mc or returning the pages to the host, resulting in a permane= nt memory leak. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260731143541.9562= 91-1-vdonnefort@google.com?part=3D9