From ac26963a1175c813e3ed21c0d2435b083173136e Mon Sep 17 00:00:00 2001 From: Brijesh Singh Date: Fri, 20 Oct 2017 09:30:57 -0500 Subject: percpu: Introduce DEFINE_PER_CPU_DECRYPTED KVM guest defines three per-CPU variables (steal-time, apf_reason, and kvm_pic_eoi) which are shared between a guest and a hypervisor. When SEV is active, memory is encrypted with a guest-specific key, and if the guest OS wants to share the memory region with the hypervisor then it must clear the C-bit (i.e set decrypted) before sharing it. DEFINE_PER_CPU_DECRYPTED can be used to define the per-CPU variables which will be shared between a guest and a hypervisor. Signed-off-by: Brijesh Singh Signed-off-by: Thomas Gleixner Tested-by: Borislav Petkov Acked-by: Tejun Heo Reviewed-by: Borislav Petkov Cc: linux-arch@vger.kernel.org Cc: Tom Lendacky Cc: kvm@vger.kernel.org Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christoph Lameter Link: https://lkml.kernel.org/r/20171020143059.3291-16-brijesh.singh@amd.com --- include/asm-generic/vmlinux.lds.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'include/asm-generic') diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 63e56f6c1877..c58f3805e348 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -777,6 +777,24 @@ #define INIT_RAM_FS #endif +/* + * Memory encryption operates on a page basis. Since we need to clear + * the memory encryption mask for this section, it needs to be aligned + * on a page boundary and be a page-size multiple in length. + * + * Note: We use a separate section so that only this section gets + * decrypted to avoid exposing more than we wish. + */ +#ifdef CONFIG_AMD_MEM_ENCRYPT +#define PERCPU_DECRYPTED_SECTION \ + . = ALIGN(PAGE_SIZE); \ + *(.data..percpu..decrypted) \ + . = ALIGN(PAGE_SIZE); +#else +#define PERCPU_DECRYPTED_SECTION +#endif + + /* * Default discarded sections. * @@ -815,6 +833,7 @@ . = ALIGN(cacheline); \ *(.data..percpu) \ *(.data..percpu..shared_aligned) \ + PERCPU_DECRYPTED_SECTION \ VMLINUX_SYMBOL(__per_cpu_end) = .; /** -- cgit v1.2.3-59-g8ed1b