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    Subject[PATCH v6 0/5] x86: Fix SEV guest regression
    Date
    The following commit

    "
    x86/kvmclock: Remove memblock dependency

    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=368a540e0232ad446931f5a4e8a5e06f69f21343
    "

    introduced SEV guest regression.

    The guest physical address holding the wall_clock and hv_clock_boot
    are shared with the hypervisor must be mapped with C=0 when SEV
    is active. To clear the C-bit we use kernel_physical_mapping_init() to
    split the large pages. The above commit moved the kvmclock initialization
    very early and kernel_physical_mapping_init() fails to allocate memory
    while spliting the large page.

    To solve it, we add a special .data..decrypted section, this section can be
    used to hold the shared variables. Early boot code maps this section with
    C=0. The section is pmd aligned and sized to avoid the need to split the pages.
    Caller can use __decrypted attribute to add the variables in .data..decrypted
    section.

    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Sean Christopherson <sean.j.christopherson@intel.com>
    Cc: "Radim Krčmář" <rkrcmar@redhat.com>

    Changes since v5:
    - rename hvclock_boot_dec -> hvclock_boot_aux.
    - rename section from .data..decrypted_aux -> .data..decrypted.aux.
    - use NR_CPUS instead of random number elements in hv_clock_aux variable.

    Changes since v4:
    - define few static pages in .data..decrypted which can be used
    for cpus > HVC_BOOT_ARRAY_SIZE when SEV is active.

    Changes since v3:
    - commit message improvements (based on Sean's feedback)

    Changes since v2:
    - commit message and code comment improvements (based on Boris feedback)
    - move sme_populate_pgd fixes in new patch.
    - drop stable Cc - will submit to stable after patch is upstreamed.

    Changes since v1:
    - move the logic to re-arrange mapping in new patch
    - move the definition of __start_data_* in mem_encrypt.h
    - map the workarea buffer as encrypted when SEV is enabled
    - enhance the sme_populate_pgd to update the pte/pmd flags when mapping exist

    Brijesh Singh (5):
    x86/mm: Restructure sme_encrypt_kernel()
    x86/mm: fix sme_populate_pgd() to update page flags
    x86/mm: add .data..decrypted section to hold shared variables
    x86/kvm: use __decrypted attribute in shared variables
    x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active

    arch/x86/include/asm/mem_encrypt.h | 10 ++
    arch/x86/kernel/head64.c | 11 ++
    arch/x86/kernel/kvmclock.c | 18 ++-
    arch/x86/kernel/vmlinux.lds.S | 20 ++++
    arch/x86/mm/init.c | 3 +
    arch/x86/mm/mem_encrypt.c | 10 ++
    arch/x86/mm/mem_encrypt_identity.c | 232 +++++++++++++++++++++++++++----------
    7 files changed, 240 insertions(+), 64 deletions(-)

    --
    2.7.4

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