From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 041DDC54EE9 for ; Tue, 20 Sep 2022 04:51:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229505AbiITEvq (ORCPT ); Tue, 20 Sep 2022 00:51:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229588AbiITEvp (ORCPT ); Tue, 20 Sep 2022 00:51:45 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E50603719F for ; Mon, 19 Sep 2022 21:51:43 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A3791B80B48 for ; Tue, 20 Sep 2022 04:51:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A84C9C433C1; Tue, 20 Sep 2022 04:51:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663649501; bh=SoECJ1jPae9bQbGGWE0oxX00MrBbsJ5OsfWBvuTX40A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PxhgSOrSpXm273goJPJ47ztQ51c+3LEqI9Fjgtu8nRZrZQcuMS/hthN67++8+pe0Z uIQ+UBgd61A0iMC8G+ufdm5bMoREay+IxTmAWFiD7hW7NEZtBMAu1+VuLA5zmyMzyx gBG7f+qKFadEImhmJeZVCwS8QtXhfjmJ7NmZt7QmoYSFNE0PgwX272SYgQGEf/KS+2 Jl6tDeUvUP6Es01CWZ5pQFjkZGbWV+cmwnDFHPg/Z9xbwIqbTI1XQ75Du5X4rEHSWL e1wfASHhAXn3YvzaY7sUAqR32TlYjHeVtXYgjs1Yzf/VCzAJHgS9svdNN3UxYyRjYs rA6F3qQfH+pEA== Date: Tue, 20 Sep 2022 07:51:36 +0300 From: Jarkko Sakkinen To: Zhiquan Li Cc: linux-sgx@vger.kernel.org, tony.luck@intel.com, dave.hansen@linux.intel.com, tglx@linutronix.de, bp@alien8.de, seanjc@google.com, kai.huang@intel.com, fan.du@intel.com, cathy.zhang@intel.com Subject: Re: [PATCH v8 2/3] x86/sgx: Introduce union with vepc_vaddr field for virtualization case Message-ID: References: <20220913145330.2998212-1-zhiquan1.li@intel.com> <20220913145330.2998212-3-zhiquan1.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220913145330.2998212-3-zhiquan1.li@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Tue, Sep 13, 2022 at 10:53:29PM +0800, Zhiquan Li wrote: > When a page triggers a machine check, it only reports the PFN. But in > order to inject #MC into hypervisor, the virtual address is required. > The 'encl_owner' field is useless in virtualization case, then > repurpose it as 'vepc_vaddr' - the virtual address of the virtual EPC > page for such case so that arch_memory_failure() can easily retrieve it. > > Introduce a union to prevent adding a new dedicated structure to > track the virtual address of virtual EPC page. And it can also prevent > playing the casting games while using it. > > Add a new EPC page flag - SGX_EPC_PAGE_KVM_GUEST to interpret the > meaning of the field. > > Co-developed-by: Cathy Zhang > Signed-off-by: Cathy Zhang > Signed-off-by: Zhiquan Li > Acked-by: Kai Huang > Reviewed-by: Jarkko Sakkinen > Acked-by: Jarkko Sakkinen Remove acked-by > > --- > Changes since V7: > - Add Acked-by from Jarkko. > > No changes since V6. > > Changes since V5: > - To prevent casting the 'encl_owner' field, introduce a union with > another field - 'vepc_vaddr', sugguested by Dave Hansen. > - Add Reviewed-by from Jarkko. > Link: https://lore.kernel.org/linux-sgx/Yrf27fugD7lkyaek@kernel.org/T/#m379d00fc7f1d43726a42b3884637532061a8c0d1 > > Changes since V4: > - Add Co-developed-by and Signed-off-by from Cathy Zhang, as she had > fully discussed the flag name with Jarkko. > Link: https://lore.kernel.org/all/df92395ade424401ac3c6322de568720@intel.com/ > - Add Acked-by from Kai Huang > Link: https://lore.kernel.org/linux-sgx/0676cd4e-d94b-e904-81ae-ca1c05d37070@intel.com/T/#mccfb11df30698dbd060f2b6f06383cda7f154ef3 > > Changes since V3: > - Take the definition of EPC page flag SGX_EPC_PAGE_KVM_GUEST from > Cathy Zhang's third patch of SGX rebootless recovery patch set but > discard irrelevant portion, since it might need some time to > re-forge and these are two different features. > Link: https://lore.kernel.org/linux-sgx/41704e5d4c03b49fcda12e695595211d950cfb08.camel@kernel.org/T/#m9782d23496cacecb7da07a67daa79f4b322ae170 > > Changes since V2: > - Remove struct sgx_vepc_page and relevant code. > - Rework the patch suggested by Jarkko. > - Remove new EPC page flag SGX_EPC_PAGE_IS_VEPC definition as it is > duplicated to SGX_EPC_PAGE_KVM_GUEST. > Link: https://lore.kernel.org/linux-sgx/eb95b32ecf3d44a695610cf7f2816785@intel.com/T/#u > > Changes since V1: > - Add documentation suggested by Jarkko. > --- > arch/x86/kernel/cpu/sgx/main.c | 4 ++++ > arch/x86/kernel/cpu/sgx/sgx.h | 8 +++++++- > arch/x86/kernel/cpu/sgx/virt.c | 4 +++- > 3 files changed, 14 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index 1315c69a733e..b319bedcaf1e 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -549,6 +549,10 @@ int sgx_unmark_page_reclaimable(struct sgx_epc_page *page) > * Finally, wake up ksgxd when the number of pages goes below the watermark > * before returning back to the caller. > * > + * When an EPC page is assigned to KVM guest, repurpose the 'encl_owner' field > + * as the virtual address of virtual EPC page, since it is useless in such > + * scenario, so 'owner' is assigned to 'vepc_vaddr'. > + * > * Return: > * an EPC page, > * -errno on error > diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h > index 4d88abccd12e..d16a8baa28d4 100644 > --- a/arch/x86/kernel/cpu/sgx/sgx.h > +++ b/arch/x86/kernel/cpu/sgx/sgx.h > @@ -28,12 +28,18 @@ > > /* Pages on free list */ > #define SGX_EPC_PAGE_IS_FREE BIT(1) > +/* Pages allocated for KVM guest */ > +#define SGX_EPC_PAGE_KVM_GUEST BIT(2) > > struct sgx_epc_page { > unsigned int section; > u16 flags; > u16 poison; > - struct sgx_encl_page *encl_owner; > + union { > + struct sgx_encl_page *encl_owner; > + /* Use when SGX_EPC_PAGE_KVM_GUEST set in ->flags: */ > + void __user *vepc_vaddr; > + }; > struct list_head list; > }; > > diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c > index 6a77a14eee38..776ae5c1c032 100644 > --- a/arch/x86/kernel/cpu/sgx/virt.c > +++ b/arch/x86/kernel/cpu/sgx/virt.c > @@ -46,10 +46,12 @@ static int __sgx_vepc_fault(struct sgx_vepc *vepc, > if (epc_page) > return 0; > > - epc_page = sgx_alloc_epc_page(vepc, false); > + epc_page = sgx_alloc_epc_page((void *)addr, false); > if (IS_ERR(epc_page)) > return PTR_ERR(epc_page); > > + epc_page->flags |= SGX_EPC_PAGE_KVM_GUEST; > + > ret = xa_err(xa_store(&vepc->page_array, index, epc_page, GFP_KERNEL)); > if (ret) > goto err_free; > -- > 2.25.1 > BR, Jarkko