Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

2019-08-13 Thread Kani, Toshi
On Tue, 2019-08-13 at 00:49 -0700, Isaku Yamahata wrote: > On Fri, Aug 09, 2019 at 07:51:17PM +, > "Kani, Toshi" wrote: > > > On Fri, 2019-08-09 at 09:06 +0200, Borislav Petkov wrote: > > > On Thu, Aug 08, 2019 at 08:54:17PM -0700, Isaku Yamahata wrote: > > > > Make PAT(Page Attribute Table)

Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

2019-08-13 Thread Borislav Petkov
On Tue, Aug 13, 2019 at 12:49:20AM -0700, Isaku Yamahata wrote: > In addition to Xen, KVM+qemu can enable/disable MTRR, PAT independently. > So user may want to disable MTRR to reduce attack surface. No, no "user may want" etc vague formulations. Just because some virt thing "can" do stuff doesn't

Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

2019-08-13 Thread Isaku Yamahata
On Fri, Aug 09, 2019 at 07:51:17PM +, "Kani, Toshi" wrote: > On Fri, 2019-08-09 at 09:06 +0200, Borislav Petkov wrote: > > On Thu, Aug 08, 2019 at 08:54:17PM -0700, Isaku Yamahata wrote: > > > Make PAT(Page Attribute Table) independent from > > > MTRR(Memory Type Range Register). > > > Some e

Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

2019-08-09 Thread Kani, Toshi
On Fri, 2019-08-09 at 09:06 +0200, Borislav Petkov wrote: > On Thu, Aug 08, 2019 at 08:54:17PM -0700, Isaku Yamahata wrote: > > Make PAT(Page Attribute Table) independent from > > MTRR(Memory Type Range Register). > > Some environments (mainly virtual ones) support only PAT, but not MTRR > > becaus

Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

2019-08-09 Thread Borislav Petkov
On Thu, Aug 08, 2019 at 08:54:17PM -0700, Isaku Yamahata wrote: > Make PAT(Page Attribute Table) independent from > MTRR(Memory Type Range Register). > Some environments (mainly virtual ones) support only PAT, but not MTRR > because PAT replaces MTRR. > It's tricky and no gain to support both MTRR

[PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

2019-08-08 Thread Isaku Yamahata
Make PAT(Page Attribute Table) independent from MTRR(Memory Type Range Register). Some environments (mainly virtual ones) support only PAT, but not MTRR because PAT replaces MTRR. It's tricky and no gain to support both MTRR and PAT except compatibility. So some VM technologies don't support MTRR,