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authorBrijesh Singh <brijesh.singh@amd.com>2017-10-20 09:30:57 -0500
committerThomas Gleixner <tglx@linutronix.de>2017-11-07 15:35:59 +0100
commitac26963a1175c813e3ed21c0d2435b083173136e (patch)
tree0142c85cd9037d5d790a10d78588409558f26b96 /include/asm-generic
parentdfaaec9033b80d71056e21cda920752e55f2c514 (diff)
downloadlinux-ac26963a1175c813e3ed21c0d2435b083173136e.tar.bz2
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 <brijesh.singh@amd.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Borislav Petkov <bp@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: linux-arch@vger.kernel.org Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: kvm@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Lameter <cl@linux.com> Link: https://lkml.kernel.org/r/20171020143059.3291-16-brijesh.singh@amd.com
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/vmlinux.lds.h19
1 files changed, 19 insertions, 0 deletions
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
@@ -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) = .;
/**