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 <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Sean Christopherson <[email protected]> Cc: "Radim Krčmář" <[email protected]> Brijesh Singh (2): x86/mm: add .data..decrypted section to hold shared variables x86/kvm: use __decrypted attribute when declaring shared variables arch/x86/include/asm/mem_encrypt.h | 4 + arch/x86/kernel/head64.c | 12 ++ arch/x86/kernel/kvmclock.c | 26 ++++- arch/x86/kernel/vmlinux.lds.S | 18 +++ arch/x86/mm/mem_encrypt_identity.c | 220 +++++++++++++++++++++++++++---------- 5 files changed, 218 insertions(+), 62 deletions(-) -- 2.7.4
