By: rwessel (rwessel.delete@this.yahoo.com), September 16, 2021 5:29 pm
Room: Moderated Discussions
anon2 (anon.delete@this.anon.com) on September 16, 2021 5:16 pm wrote:
> Carson (carson.delete@this.example.edu) on September 16, 2021 1:12 pm wrote:
> > But this whole situation shows how nightmarish it is preventing Meltdown attacks in the presence of virtual
> > aliasing. Because the store could take a long time (page table walking) to be fully resolved, and the load
> > does not alias nine-nines of the time, we really can't afford to wait before proceeding speculatively.
>
> It's not really bad. It is somewhat like spectre variant 4. This is no problem with such speculation
> within a privilege domain. Between domains like a system call then you need to ensure prior
> stores are executed at least to a point where speculative data would not be used.
z15 actually added an instruction (or more specifically a new function for Perform Processor Assist) to force that. Presumably the OS uses it on some task switches.
> Carson (carson.delete@this.example.edu) on September 16, 2021 1:12 pm wrote:
> > But this whole situation shows how nightmarish it is preventing Meltdown attacks in the presence of virtual
> > aliasing. Because the store could take a long time (page table walking) to be fully resolved, and the load
> > does not alias nine-nines of the time, we really can't afford to wait before proceeding speculatively.
>
> It's not really bad. It is somewhat like spectre variant 4. This is no problem with such speculation
> within a privilege domain. Between domains like a system call then you need to ensure prior
> stores are executed at least to a point where speculative data would not be used.
z15 actually added an instruction (or more specifically a new function for Perform Processor Assist) to force that. Presumably the OS uses it on some task switches.
| Topic | Posted By | Date |
|---|---|---|
| POWER10 SAP SD benchmark | anon2 | 2021/09/06 02:36 PM |
| POWER10 SAP SD benchmark | Daniel B | 2021/09/07 01:31 AM |
| "Cores" (and SPEC) | Rayla | 2021/09/07 06:51 AM |
| "Cores" (and SPEC) | anon | 2021/09/07 02:56 PM |
| POWER10 SAP SD benchmark | Anon | 2021/09/07 02:24 PM |
| POWER10 SAP SD benchmark | Anon | 2021/09/07 02:27 PM |
| Virtually tagged L1-caches | sr | 2021/09/08 04:49 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/08 07:22 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 07:56 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/08 07:58 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 09:09 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/08 09:46 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 10:35 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/08 11:23 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 11:40 AM |
| Virtually tagged L1-caches | anon | 2021/09/09 02:16 AM |
| Virtually tagged L1-caches | Konrad Schwarz | 2021/09/10 04:19 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/10 05:59 AM |
| Virtually tagged L1-caches | anon | 2021/09/14 02:17 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/14 08:34 AM |
| Or use a PLB (NT) | Paul A. Clayton | 2021/09/14 08:45 AM |
| Or use a PLB | Linus Torvalds | 2021/09/14 02:27 PM |
| Or use a PLB | anon | 2021/09/14 11:15 PM |
| Or use a PLB | Michael S | 2021/09/15 02:21 AM |
| Or use a PLB | dmcq | 2021/09/15 02:42 PM |
| Or use a PLB | Konrad Schwarz | 2021/09/16 03:24 AM |
| Or use a PLB | Michael S | 2021/09/16 09:13 AM |
| Or use a PLB | --- | 2021/09/16 12:02 PM |
| PLB reference | Paul A. Clayton | 2021/09/18 01:35 PM |
| PLB reference | Michael S | 2021/09/18 03:14 PM |
| Demand paging/translation orthogonal | Paul A. Clayton | 2021/09/19 06:33 AM |
| Demand paging/translation orthogonal | Michael S | 2021/09/19 08:10 AM |
| PLB reference | Carson | 2021/09/20 09:19 PM |
| PLB reference | sr | 2021/09/20 05:02 AM |
| PLB reference | Michael S | 2021/09/20 06:03 AM |
| PLB reference | Linus Torvalds | 2021/09/20 11:10 AM |
| Or use a PLB | sr | 2021/09/20 03:32 AM |
| Or use a PLB | sr | 2021/09/21 08:36 AM |
| Or use a PLB | Linus Torvalds | 2021/09/21 09:04 AM |
| Or use a PLB | sr | 2021/09/21 09:48 AM |
| Or use a PLB | Linus Torvalds | 2021/09/21 12:55 PM |
| Or use a PLB | sr | 2021/09/22 05:55 AM |
| Or use a PLB | rwessel | 2021/09/22 06:09 AM |
| Or use a PLB | Linus Torvalds | 2021/09/22 10:50 AM |
| Or use a PLB | sr | 2021/09/22 12:00 PM |
| Or use a PLB | dmcq | 2021/09/22 03:07 PM |
| Or use a PLB | Etienne Lorrain | 2021/09/23 07:50 AM |
| Or use a PLB | anon2 | 2021/09/22 03:09 PM |
| Or use a PLB | dmcq | 2021/09/23 01:35 AM |
| Or use a PLB | ⚛ | 2021/09/23 08:37 AM |
| Or use a PLB | Linus Torvalds | 2021/09/23 11:01 AM |
| Or use a PLB | gpd | 2021/09/24 02:59 AM |
| Or use a PLB | Linus Torvalds | 2021/09/24 09:45 AM |
| Or use a PLB | dmcq | 2021/09/24 11:43 AM |
| Or use a PLB | sr | 2021/09/25 09:19 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 09:44 AM |
| Or use a PLB | sr | 2021/09/25 10:11 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 10:31 AM |
| Or use a PLB | sr | 2021/09/25 10:52 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 11:05 AM |
| Or use a PLB | sr | 2021/09/25 11:23 AM |
| Or use a PLB | rwessel | 2021/09/25 02:29 PM |
| Or use a PLB | sr | 2021/09/30 11:22 PM |
| Or use a PLB | rwessel | 2021/10/01 05:19 AM |
| Or use a PLB | David Hess | 2021/10/01 09:35 AM |
| Or use a PLB | rwessel | 2021/10/02 03:47 AM |
| Or use a PLB | sr | 2021/10/02 10:16 AM |
| Or use a PLB | rwessel | 2021/10/02 10:53 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 10:57 AM |
| Or use a PLB | sr | 2021/09/25 11:07 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 11:21 AM |
| Or use a PLB | sr | 2021/09/25 11:40 AM |
| Or use a PLB | nksingh | 2021/09/27 08:07 AM |
| Or use a PLB | ⚛ | 2021/09/27 08:02 AM |
| Or use a PLB | Linus Torvalds | 2021/09/27 09:20 AM |
| Or use a PLB | Linus Torvalds | 2021/09/27 11:58 AM |
| Or use a PLB | dmcq | 2021/09/28 09:59 AM |
| Or use a PLB | sr | 2021/09/25 09:34 AM |
| Or use a PLB | rwessel | 2021/09/25 02:44 PM |
| Or use a PLB | sr | 2021/10/01 12:04 AM |
| Or use a PLB | rwessel | 2021/10/01 05:33 AM |
| I386 segmentation highlights | sr | 2021/10/04 06:53 AM |
| I386 segmentation highlights | Adrian | 2021/10/04 08:53 AM |
| I386 segmentation highlights | sr | 2021/10/04 09:19 AM |
| I386 segmentation highlights | rwessel | 2021/10/04 03:57 PM |
| I386 segmentation highlights | sr | 2021/10/05 10:16 AM |
| I386 segmentation highlights | Michael S | 2021/10/05 11:27 AM |
| I386 segmentation highlights | rwessel | 2021/10/05 03:20 PM |
| Or use a PLB | JohnG | 2021/09/25 09:18 PM |
| Or use a PLB | ⚛ | 2021/09/27 06:37 AM |
| Or use a PLB | Heikki Kultala | 2021/09/28 02:53 AM |
| Or use a PLB | rwessel | 2021/09/28 06:29 AM |
| Or use a PLB | David Hess | 2021/09/23 05:00 PM |
| Or use a PLB | Adrian | 2021/09/24 12:21 AM |
| Or use a PLB | dmcq | 2021/09/25 11:41 AM |
| Or use a PLB | blaine | 2021/09/26 10:19 PM |
| Or use a PLB | David Hess | 2021/09/27 10:35 AM |
| Or use a PLB | blaine | 2021/09/27 04:19 PM |
| Or use a PLB | Adrian | 2021/09/27 09:40 PM |
| Or use a PLB | Adrian | 2021/09/27 09:59 PM |
| Or use a PLB | dmcq | 2021/09/28 06:45 AM |
| Or use a PLB | rwessel | 2021/09/28 06:45 AM |
| Or use a PLB | David Hess | 2021/09/28 11:50 AM |
| Or use a PLB | Etienne Lorrain | 2021/09/30 12:25 AM |
| Or use a PLB | David Hess | 2021/10/01 09:40 AM |
| MMU privileges | sr | 2021/09/21 10:07 AM |
| MMU privileges | Linus Torvalds | 2021/09/21 12:49 PM |
| Virtually tagged L1-caches | Konrad Schwarz | 2021/09/16 03:18 AM |
| Virtually tagged L1-caches | Carson | 2021/09/16 12:12 PM |
| Virtually tagged L1-caches | anon2 | 2021/09/16 04:16 PM |
| Virtually tagged L1-caches | rwessel | 2021/09/16 05:29 PM |
| Virtually tagged L1-caches | sr | 2021/09/20 03:20 AM |
| Virtually tagged L1-caches | --- | 2021/09/08 01:28 PM |
| Virtually tagged L1-caches | anonymou5 | 2021/09/08 07:28 PM |
| Virtually tagged L1-caches | anonymou5 | 2021/09/08 07:34 PM |
| Virtually tagged L1-caches | --- | 2021/09/09 09:14 AM |
| Virtually tagged L1-caches | anonymou5 | 2021/09/09 09:44 PM |
| Multi-threading? | David Kanter | 2021/09/09 08:32 PM |
| Multi-threading? | --- | 2021/09/10 08:19 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 12:19 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 12:36 AM |
| Virtually tagged L1-caches | --- | 2021/09/11 08:53 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 11:43 PM |
| Virtually tagged L1-caches | Linus Torvalds | 2021/09/12 10:10 AM |
| Virtually tagged L1-caches | sr | 2021/09/12 10:57 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/13 07:31 AM |
| Virtually tagged L1-caches | sr | 2021/09/20 03:11 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 01:49 AM |
| Virtually tagged L1-caches | Linus Torvalds | 2021/09/08 11:34 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/09 01:46 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/09 01:58 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 12:29 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/11 07:59 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 11:57 PM |
| Virtually tagged L1-caches | dmcq | 2021/09/12 07:44 AM |
| Virtually tagged L1-caches | sr | 2021/09/12 08:48 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/12 12:22 PM |
| Virtually tagged L1-caches | sr | 2021/09/20 03:40 AM |
| Where do you see this information? (NT) | anon2 | 2021/09/09 01:45 AM |
| Where do you see this information? | sr | 2021/09/11 12:40 AM |
| Where do you see this information? | anon2 | 2021/09/11 12:53 AM |
| Where do you see this information? | sr | 2021/09/11 01:08 AM |
| Thank you (NT) | anon2 | 2021/09/11 03:31 PM |
