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Peter Anvin" , Juergen Gross , Stefano Stabellini , "Michael S. Tsirkin" , Jason Wang , Dave Young , Baoquan He , Vivek Goyal , Michal Hocko , Oscar Salvador , Mike Rapoport , "Rafael J. Wysocki" , x86@kernel.org, xen-devel@lists.xenproject.org, virtualization@lists.linux-foundation.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20210928182258.12451-1-david@redhat.com> <20210928182258.12451-3-david@redhat.com> <4ab2f8c2-c3d5-30b3-a670-a8b38e218b6e@oracle.com> From: Boris Ostrovsky Message-ID: <3b935aa0-6d85-0bcd-100e-15098add3c4c@oracle.com> Date: Wed, 29 Sep 2021 10:22:07 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-ClientProxiedBy: BLAPR03CA0135.namprd03.prod.outlook.com (2603:10b6:208:32e::20) To BLAPR10MB5009.namprd10.prod.outlook.com (2603:10b6:208:321::10) MIME-Version: 1.0 Received: from [10.74.99.231] (160.34.89.231) by BLAPR03CA0135.namprd03.prod.outlook.com (2603:10b6:208:32e::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.15 via Frontend Transport; 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>> -       int ram; >>    -       if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a)) >> -               return -ENXIO; >> - >> -       switch (a.mem_type) { >> -       case HVMMEM_mmio_dm: >> -               ram = 0; >> -               break; >> -       case HVMMEM_ram_rw: >> -       case HVMMEM_ram_ro: >> -       default: >> -               ram = 1; >> -               break; >> -       } >> - >> -       return ram; >> +       HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a); >> +       return a.mem_type != HVMMEM_mmio_dm; I was actually thinking of asking you to add another patch with pr_warn_once() here (and print error code as well). This call failing is indication of something going quite wrong and it would be good to know about this. >>    } >>    #endif >> >> >> Assuming that if HYPERVISOR_hvm_op() fails that >> .mem_type is not set to HVMMEM_mmio_dm. I don't think we can assume that argument described as OUT in the ABI will not be clobbered in case of error >> > > Okay we can't, due to "__must_check" ... so this is a good thing ;-) -boris