Commit-ID: ac26963a1175c813e3ed21c0d2435b083173136e Gitweb: https://git.kernel.org/tip/ac26963a1175c813e3ed21c0d2435b083173136e Author: Brijesh Singh <[email protected]> AuthorDate: Fri, 20 Oct 2017 09:30:57 -0500 Committer: Thomas Gleixner <[email protected]> CommitDate: Tue, 7 Nov 2017 15:35:59 +0100
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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Borislav Petkov <[email protected]> Acked-by: Tejun Heo <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Cc: [email protected] Cc: Tom Lendacky <[email protected]> Cc: [email protected] Cc: Arnd Bergmann <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Christoph Lameter <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- include/asm-generic/vmlinux.lds.h | 19 +++++++++++++++++++ include/linux/percpu-defs.h | 15 +++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 63e56f6..c58f380 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -778,6 +778,24 @@ #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. * * Some archs want to discard exit text/data at runtime rather than @@ -815,6 +833,7 @@ . = ALIGN(cacheline); \ *(.data..percpu) \ *(.data..percpu..shared_aligned) \ + PERCPU_DECRYPTED_SECTION \ VMLINUX_SYMBOL(__per_cpu_end) = .; /** diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h index 8f16299..2d2096b 100644 --- a/include/linux/percpu-defs.h +++ b/include/linux/percpu-defs.h @@ -173,6 +173,21 @@ DEFINE_PER_CPU_SECTION(type, name, "..read_mostly") /* + * Declaration/definition used for per-CPU variables that should be accessed + * as decrypted when memory encryption is enabled in the guest. + */ +#if defined(CONFIG_VIRTUALIZATION) && defined(CONFIG_AMD_MEM_ENCRYPT) + +#define DECLARE_PER_CPU_DECRYPTED(type, name) \ + DECLARE_PER_CPU_SECTION(type, name, "..decrypted") + +#define DEFINE_PER_CPU_DECRYPTED(type, name) \ + DEFINE_PER_CPU_SECTION(type, name, "..decrypted") +#else +#define DEFINE_PER_CPU_DECRYPTED(type, name) DEFINE_PER_CPU(type, name) +#endif + +/* * Intermodule exports for per-CPU variables. sparse forgets about * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to * noop if __CHECKER__.
