Messages in this thread | | | Date | Fri, 4 Feb 2022 11:21:28 -0800 | From | Ira Weiny <> | Subject | Re: [PATCH V8 07/44] x86/pkeys: Add PKS CPU feature bit |
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On Fri, Jan 28, 2022 at 03:05:36PM -0800, Dave Hansen wrote: > On 1/27/22 09:54, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > > > Protection Keys for Supervisor pages (PKS) enables fast, hardware thread > > specific, manipulation of permission restrictions on supervisor page > > Nit: should be "hardware-thread-specific". > > > mappings. It uses the same mechanism of Protection Keys as those on > > User mappings but applies that mechanism to supervisor mappings using a > > supervisor specific MSR. > > "supervisor-specific" > > Memory Protection Keys (pkeys) provides a mechanism for > enforcing page-based protections, but without requiring > modification of the page tables when an application changes > protection domains. > > The kernel currently supports the pkeys for userspace (PKU) > architecture. That architecture has been extended to > additionally support supervisor mappings. The supervisor > support is referred to as PKS. > > I probably wouldn't mention the MSR unless you want to say: > > The main difference between PKU and PKS is that PKS does not > introduce any new instructions to write to its register. The > register is exposed as a normal MSR and is accessed with the > normal MSR instructions. > > > > The CPU indicates support for PKS in bit 31 of the ECX register after a > > cpuid instruction. > > I'd just remove this sentence. We don't need to rehash each tiny morsel > of the architecture in a commit message.
All done. Thanks for the verbiage. Ira
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