[Part1 PATCH v4 15/17] percpu: introduce DEFINE_PER_CPU_UNENCRYPTED
From: Brijesh Singh <hidden>
Date: 2017-09-16 12:36:05
Also in:
linux-arch, lkml
Subsystem:
generic include/asm header files, per-cpu memory allocator, the rest · Maintainers:
Arnd Bergmann, Dennis Zhou, Tejun Heo, Christoph Lameter, Linus Torvalds
When SEV is active, memory is encrypted with guest-specific key, and if guest OS wants to share the memory region with hypervisor then it must clear the C-bit (i.e set unencrypted) before sharing it. DEFINE_PER_CPU_UNENCRYPTED can be used to define the per-cpu variables which will be shared between guest and hypervisor. Currently, KVM defines three variables (steal-time, apf_reason, and avic_eio) which are shared with hypervisor. Cc: Thomas Gleixner <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Borislav Petkov <redacted> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <redacted> Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Cc: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Brijesh Singh <redacted> --- include/asm-generic/vmlinux.lds.h | 11 +++++++++++ include/linux/percpu-defs.h | 15 +++++++++++++++ 2 files changed, 26 insertions(+)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 8acfc1e099e1..363858f43cbc 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h@@ -777,6 +777,16 @@ #define INIT_RAM_FS #endif +#ifdef CONFIG_AMD_MEM_ENCRYPT +#define PERCPU_UNENCRYPTED_SECTION \ + . = ALIGN(PAGE_SIZE); \ + *(.data..percpu..unencrypted) \ + . = ALIGN(PAGE_SIZE); +#else +#define PERCPU_UNENCRYPTED_SECTION +#endif + + /* * Default discarded sections. *
@@ -815,6 +825,7 @@ . = ALIGN(cacheline); \ *(.data..percpu) \ *(.data..percpu..shared_aligned) \ + PERCPU_UNENCRYPTED_SECTION \ VMLINUX_SYMBOL(__per_cpu_end) = .; /**
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 8f16299ca068..b2b99ad4b31d 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 unencrypted when memory encryption is enabled in the guest. + */ +#if defined(CONFIG_VIRTUALIZATION) && defined(CONFIG_AMD_MEM_ENCRYPT) + +#define DECLARE_PER_CPU_UNENCRYPTED(type, name) \ + DECLARE_PER_CPU_SECTION(type, name, "..unencrypted") + +#define DEFINE_PER_CPU_UNENCRYPTED(type, name) \ + DEFINE_PER_CPU_SECTION(type, name, "..unencrypted") +#else +#define DEFINE_PER_CPU_UNENCRYPTED(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__.
--
2.9.5