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). The main use cases are Xen PV guests and SEV-SNP guests running under Hyper-V. 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. 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". I have added more cleanup which has been discussed when looking into the most recent failures. Note that I couldn't test the Hyper-V related change (patch 3). Running on bare metal and with Xen didn't show any problems with the series applied. 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) Juergen Gross (8): x86/mtrr: split off physical address size calculation 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: revert commit 90b926e68f50 x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID x86/mm: only check uniform after calling mtrr_type_lookup() x86/mtrr: drop sanity check in mtrr_type_lookup_fixed() arch/x86/include/asm/mtrr.h | 9 +++- arch/x86/include/uapi/asm/mtrr.h | 6 +-- arch/x86/kernel/cpu/mshyperv.c | 8 +++ arch/x86/kernel/cpu/mtrr/generic.c | 56 +++++++++++++++++---- arch/x86/kernel/cpu/mtrr/mtrr.c | 79 ++++++++++++++++-------------- arch/x86/mm/pat/memtype.c | 3 +- arch/x86/mm/pgtable.c | 6 +-- arch/x86/xen/enlighten_pv.c | 49 ++++++++++++++++++ 8 files changed, 159 insertions(+), 57 deletions(-) -- 2.35.3
