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. It should be noted that patches 9+10 are replacing today's way to lookup the MTRR cache type for a memory region from looking at the MTRR register values to building a memory map with the cache types. This should make the lookup much faster and much easier to understand. 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) Changes in V3: - dropped patch 5 of V2, as already applied - split patch 1 of V2 into 2 patches - new patches 6-10 - addressed comments Changes in V4: - addressed comments Changes in V5 - addressed comments - some other small fixes - new patches 3, 8 and 15 Changes in V6: - patch 1 replaces patches 1+2 of V5 - new patches 8+12 - addressed comments Juergen Gross (16): x86/mtrr: remove physical address size calculation x86/mtrr: replace some constants with defines 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: replace vendor tests in MTRR code x86/mtrr: have only one set_mtrr() variant x86/mtrr: move 32-bit code from mtrr.c to legacy.c x86/mtrr: allocate mtrr_value array dynamically x86/mtrr: add get_effective_type() service function x86/mtrr: construct a memory map with cache modes x86/mtrr: add mtrr=debug command line option x86/mtrr: use new cache_map in mtrr_type_lookup() x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID x86/mm: only check uniform after calling mtrr_type_lookup() x86/mtrr: remove unused code .../admin-guide/kernel-parameters.txt | 4 + arch/x86/hyperv/ivm.c | 4 + arch/x86/include/asm/mtrr.h | 43 +- arch/x86/include/uapi/asm/mtrr.h | 6 +- arch/x86/kernel/cpu/mtrr/Makefile | 2 +- arch/x86/kernel/cpu/mtrr/amd.c | 2 +- arch/x86/kernel/cpu/mtrr/centaur.c | 11 +- arch/x86/kernel/cpu/mtrr/cleanup.c | 22 +- arch/x86/kernel/cpu/mtrr/cyrix.c | 2 +- arch/x86/kernel/cpu/mtrr/generic.c | 677 ++++++++++++------ arch/x86/kernel/cpu/mtrr/legacy.c | 90 +++ arch/x86/kernel/cpu/mtrr/mtrr.c | 195 ++--- arch/x86/kernel/cpu/mtrr/mtrr.h | 18 +- arch/x86/kernel/setup.c | 2 + arch/x86/mm/pgtable.c | 24 +- arch/x86/xen/enlighten_pv.c | 52 ++ 16 files changed, 721 insertions(+), 433 deletions(-) create mode 100644 arch/x86/kernel/cpu/mtrr/legacy.c -- 2.35.3
