lkml.org 
[lkml]   [2023]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRE: [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR
    Date
    From: Juergen Gross <jgross@suse.com> Sent: Monday, March 6, 2023 8:34 AM
    >
    > 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
    >
    > Juergen Gross (12):
    > x86/mtrr: split off physical address size calculation
    > x86/mtrr: optimize mtrr_calc_physbits()
    > 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: allocate mtrr_value array dynamically
    > x86/mtrr: add get_effective_type() service function
    > x86/mtrr: construct a memory map with cache modes
    > 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()
    >
    > arch/x86/include/asm/mtrr.h | 15 +-
    > arch/x86/include/uapi/asm/mtrr.h | 6 +-
    > arch/x86/kernel/cpu/mshyperv.c | 4 +
    > arch/x86/kernel/cpu/mtrr/amd.c | 2 +-
    > arch/x86/kernel/cpu/mtrr/centaur.c | 2 +-
    > arch/x86/kernel/cpu/mtrr/cleanup.c | 4 +-
    > arch/x86/kernel/cpu/mtrr/cyrix.c | 2 +-
    > arch/x86/kernel/cpu/mtrr/generic.c | 492 ++++++++++++++++++-----------
    > arch/x86/kernel/cpu/mtrr/mtrr.c | 94 +++---
    > arch/x86/kernel/cpu/mtrr/mtrr.h | 7 +-
    > arch/x86/kernel/setup.c | 2 +
    > arch/x86/mm/pgtable.c | 24 +-
    > arch/x86/xen/enlighten_pv.c | 52 +++
    > 13 files changed, 454 insertions(+), 252 deletions(-)
    >
    > --
    > 2.35.3

    I've tested a Linux 6.2 kernel plus this series in a normal Hyper-V
    guest and in a Hyper-V guest using SEV-SNP with vTOM. MMIO
    memory is correctly mapped as WB or UC- depending on the
    request, which fixes the original problem introduced for Hyper-V
    by the Xen-specific change.

    Tested-by: Michael Kelley <mikelley@microsoft.com>

    \
     
     \ /
      Last update: 2023-03-27 00:48    [W:5.760 / U:0.052 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site