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Peter Anvin" , KY Srinivasan , Haiyang Zhang , Wei Liu , Dexuan Cui , Boris Ostrovsky , "xen-devel@lists.xenproject.org" , Jonathan Corbet , Andy Lutomirski , Peter Zijlstra Subject: RE: [PATCH v6 00/16] x86/mtrr: fix handling with PAT but without MTRR Thread-Topic: [PATCH v6 00/16] x86/mtrr: fix handling with PAT but without MTRR Thread-Index: AQHZfO8AidMlTOanxE29vr+R9vbz+69H8llg Date: Wed, 3 May 2023 04:22:47 +0000 Message-ID: References: <20230502120931.20719-1-jgross@suse.com> In-Reply-To: <20230502120931.20719-1-jgross@suse.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_ActionId=623c2fcc-89cf-47dd-a85a-04fd8fadfa20;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_ContentBits=0;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Enabled=true;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Method=Standard;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Name=Internal;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_SetDate=2023-05-03T04:17:01Z;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_SiteId=72f988bf-86f1-41af-91ab-2d7cd011db47; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BYAPR21MB1688.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0c1bf722-548b-4607-f879-08db4b8e0cba X-MS-Exchange-CrossTenant-originalarrivaltime: 03 May 2023 04:22:47.3546 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: F4oz+y3a+0Vw8WA7Yyy7owpm/xWojADSC5j6iYwY6aydHvqP9XDf88eWc5mo3pwV5g7MITimVS8bEgxbVTFOLHfvMUMBbAfxxuOAAsxlbEw= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ1PR21MB3672 X-Spam-Status: No, score=-2.3 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Juergen Gross Sent: Tuesday, May 2, 2023 5:09 AM >=20 > This series tries to fix the rather special case of PAT being available > without having MTRRs (either due to CONFIG_MTRR being not set, or > because the feature has been disabled e.g. by a hypervisor). >=20 > The main use cases are Xen PV guests and SEV-SNP guests running under > Hyper-V. >=20 > Instead of trying to work around all the issues by adding if statements > here and there, just try to use the complete available infrastructure > by setting up a read-only MTRR state when needed. >=20 > In the Xen PV case the current MTRR MSR values can be read from the > hypervisor, while for the SEV-SNP case all needed is to set the > default caching mode to "WB". >=20 > I have added more cleanup which has been discussed when looking into > the most recent failures. >=20 > Note that I couldn't test the Hyper-V related change (patch 3). >=20 > Running on bare metal and with Xen didn't show any problems with the > series applied. >=20 > It should be noted that patches 9+10 are replacing today's way to > lookup the MTRR cache type for a memory region from looking at the > MTRR register values to building a memory map with the cache types. > This should make the lookup much faster and much easier to understand. >=20 > Changes in V2: > - replaced former patches 1+2 with new patches 1-4, avoiding especially > the rather hacky approach of V1, while making all the MTRR type > conflict tests available for the Xen PV case > - updated patch 6 (was patch 4 in V1) >=20 > Changes in V3: > - dropped patch 5 of V2, as already applied > - split patch 1 of V2 into 2 patches > - new patches 6-10 > - addressed comments >=20 > Changes in V4: > - addressed comments >=20 > Changes in V5 > - addressed comments > - some other small fixes > - new patches 3, 8 and 15 >=20 > Changes in V6: > - patch 1 replaces patches 1+2 of V5 > - new patches 8+12 > - addressed comments >=20 > Juergen Gross (16): > x86/mtrr: remove physical address size calculation > x86/mtrr: replace some constants with defines > x86/mtrr: support setting MTRR state for software defined MTRRs > x86/hyperv: set MTRR state when running as SEV-SNP Hyper-V guest > x86/xen: set MTRR state when running as Xen PV initial domain > x86/mtrr: replace vendor tests in MTRR code > x86/mtrr: have only one set_mtrr() variant > x86/mtrr: move 32-bit code from mtrr.c to legacy.c > x86/mtrr: allocate mtrr_value array dynamically > x86/mtrr: add get_effective_type() service function > x86/mtrr: construct a memory map with cache modes > x86/mtrr: add mtrr=3Ddebug command line option > x86/mtrr: use new cache_map in mtrr_type_lookup() > x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID > x86/mm: only check uniform after calling mtrr_type_lookup() > x86/mtrr: remove unused code >=20 > .../admin-guide/kernel-parameters.txt | 4 + > arch/x86/hyperv/ivm.c | 4 + > arch/x86/include/asm/mtrr.h | 43 +- > arch/x86/include/uapi/asm/mtrr.h | 6 +- > arch/x86/kernel/cpu/mtrr/Makefile | 2 +- > arch/x86/kernel/cpu/mtrr/amd.c | 2 +- > arch/x86/kernel/cpu/mtrr/centaur.c | 11 +- > arch/x86/kernel/cpu/mtrr/cleanup.c | 22 +- > arch/x86/kernel/cpu/mtrr/cyrix.c | 2 +- > arch/x86/kernel/cpu/mtrr/generic.c | 677 ++++++++++++------ > arch/x86/kernel/cpu/mtrr/legacy.c | 90 +++ > arch/x86/kernel/cpu/mtrr/mtrr.c | 195 ++--- > arch/x86/kernel/cpu/mtrr/mtrr.h | 18 +- > arch/x86/kernel/setup.c | 2 + > arch/x86/mm/pgtable.c | 24 +- > arch/x86/xen/enlighten_pv.c | 52 ++ > 16 files changed, 721 insertions(+), 433 deletions(-) > create mode 100644 arch/x86/kernel/cpu/mtrr/legacy.c >=20 > -- > 2.35.3 I've tested the full v6 series in a normal Hyper-V guest and in an SEV-SNP = guest. In the SNP guest, the page attributes in /sys/kernel/debug/x86/pat_memtype_= list are "write-back" in the expected cases. The "mtrr" x86 feature no longer a= ppears in the "flags" output of "lscpu" or /proc/cpuinfo. /proc/mtrr does not exi= st, again as expected. In a normal VM, the "mtrr" x86 feature appears in the flags, and /proc/mtrr shows expected values. The boot option mtrr=3Ddebug works as expected. Tested-by: Michael Kelley