[PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-08-30 Thread Jan Beulich
One of the changes comprising the fixes for XSA-378 disallows replacing MMIO mappings by unintended (for this purpose) code paths. At least in the case of PVH Dom0 hitting an RMRR covered by an E820 ACPI region, this is too strict. Generally short-circuit requests establishing the same kind of mapp

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-06 Thread Andrew Cooper
On 01/09/2021 14:08, Jan Beulich wrote: Restricting execute permissions is something unique to virt.  It doesn't exist in a non-virtualised system, as I and D side reads are indistinguishable outside of the core. Furthermore, it is inexpressible on some systems/configuratio

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-06 Thread Jan Beulich
On 06.09.2021 21:53, Andrew Cooper wrote: > On 01/09/2021 14:08, Jan Beulich wrote: > Restricting execute permissions is something unique to virt.  It doesn't > exist in a non-virtualised system, as I and D side reads are > indistinguishable outside of the core. > > Furthermore,

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-08-31 Thread Jan Beulich
On 30.08.2021 15:02, Jan Beulich wrote: > One of the changes comprising the fixes for XSA-378 disallows replacing > MMIO mappings by unintended (for this purpose) code paths. At least in > the case of PVH Dom0 hitting an RMRR covered by an E820 ACPI region, > this is too strict. Generally short-cir

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-08-31 Thread Andrew Cooper
On 30/08/2021 14:02, Jan Beulich wrote: > One of the changes comprising the fixes for XSA-378 disallows replacing > MMIO mappings by unintended (for this purpose) code paths. Drop the brackets. > At least in > the case of PVH Dom0 hitting an RMRR covered by an E820 ACPI region, > this is too stri

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-08-31 Thread Jan Beulich
On 31.08.2021 15:16, Andrew Cooper wrote: > On 30/08/2021 14:02, Jan Beulich wrote: >> Further permit "access" to differ in the "executable" attribute. While >> ideally only ROM regions would get mapped with X set, getting there is >> quite a bit of work. Therefore, as a temporary measure, permit X

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-08-31 Thread Andrew Cooper
On 31/08/2021 14:26, Jan Beulich wrote: > On 31.08.2021 15:16, Andrew Cooper wrote: >> On 30/08/2021 14:02, Jan Beulich wrote: >>> Further permit "access" to differ in the "executable" attribute. While >>> ideally only ROM regions would get mapped with X set, getting there is >>> quite a bit of wor

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-08-31 Thread Jan Beulich
On 31.08.2021 17:25, Andrew Cooper wrote: > On 31/08/2021 14:26, Jan Beulich wrote: >> On 31.08.2021 15:16, Andrew Cooper wrote: >>> On 30/08/2021 14:02, Jan Beulich wrote: Further permit "access" to differ in the "executable" attribute. While ideally only ROM regions would get mapped wit

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Jan Beulich
On 31.08.2021 17:38, Jan Beulich wrote: > On 31.08.2021 17:25, Andrew Cooper wrote: >> On 31/08/2021 14:26, Jan Beulich wrote: >>> On 31.08.2021 15:16, Andrew Cooper wrote: On 30/08/2021 14:02, Jan Beulich wrote: > Further permit "access" to differ in the "executable" attribute. While

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Roger Pau Monné
On Tue, Aug 31, 2021 at 05:38:49PM +0200, Jan Beulich wrote: > On 31.08.2021 17:25, Andrew Cooper wrote: > > On 31/08/2021 14:26, Jan Beulich wrote: > >> On 31.08.2021 15:16, Andrew Cooper wrote: > >>> On 30/08/2021 14:02, Jan Beulich wrote: > Further permit "access" to differ in the "executab

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Jan Beulich
On 01.09.2021 10:50, Roger Pau Monné wrote: > On Tue, Aug 31, 2021 at 05:38:49PM +0200, Jan Beulich wrote: >> On 31.08.2021 17:25, Andrew Cooper wrote: >>> On 31/08/2021 14:26, Jan Beulich wrote: On 31.08.2021 15:16, Andrew Cooper wrote: > On 30/08/2021 14:02, Jan Beulich wrote: >> Fur

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Andrew Cooper
On 31/08/2021 16:38, Jan Beulich wrote: > On 31.08.2021 17:25, Andrew Cooper wrote: >> On 31/08/2021 14:26, Jan Beulich wrote: >>> On 31.08.2021 15:16, Andrew Cooper wrote: On 30/08/2021 14:02, Jan Beulich wrote: > Further permit "access" to differ in the "executable" attribute. While

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Jan Beulich
On 01.09.2021 14:47, Andrew Cooper wrote: > On 31/08/2021 16:38, Jan Beulich wrote: >> On 31.08.2021 17:25, Andrew Cooper wrote: >>> On 31/08/2021 14:26, Jan Beulich wrote: On 31.08.2021 15:16, Andrew Cooper wrote: > On 30/08/2021 14:02, Jan Beulich wrote: >> Further permit "access" to

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Roger Pau Monné
On Wed, Sep 01, 2021 at 11:53:03AM +0200, Jan Beulich wrote: > On 01.09.2021 10:50, Roger Pau Monné wrote: > > On Tue, Aug 31, 2021 at 05:38:49PM +0200, Jan Beulich wrote: > >> On 31.08.2021 17:25, Andrew Cooper wrote: > >>> On 31/08/2021 14:26, Jan Beulich wrote: > On 31.08.2021 15:16, Andrew

Re: [PATCH 2/4] x86/P2M: relax guarding of MMIO entries

2021-09-01 Thread Jan Beulich
On 01.09.2021 15:48, Roger Pau Monné wrote: > On Wed, Sep 01, 2021 at 11:53:03AM +0200, Jan Beulich wrote: >> The issue isn't just with execution, though, and as a result I may >> need to change the logic here to also include at least W. As of >> one of the XSA-378 changes we may now pass just p2m_