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@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx> Changes since v8: - restore the C-bit before freeing unused decrypted memory - fix compiler warning when NR_CPUS=1 Changes since v7: - As per Thomas Gleixner suggestion move the decrypted data in .bss..decrypted section - remove the second auxiliary array from SEV case - allocate memory for pvclock data pointer early and map with C=0 for SEV case Changes since v6: - improve commit messages - rename free_decrypted_mem -> mem_encrypt_free_decrypted_mem 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 (2): x86/mm: add .bss..decrypted section to hold shared variables x86/kvm: use __bss_decrypted attribute in shared variables arch/x86/include/asm/mem_encrypt.h | 7 +++++ arch/x86/kernel/head64.c | 16 ++++++++++++ arch/x86/kernel/kvmclock.c | 52 +++++++++++++++++++++++++++++++++++--- arch/x86/kernel/vmlinux.lds.S | 19 ++++++++++++++ arch/x86/mm/init.c | 4 +++ arch/x86/mm/mem_encrypt.c | 24 ++++++++++++++++++ 6 files changed, 119 insertions(+), 3 deletions(-) -- 2.7.4
