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authorBrijesh Singh <brijesh.singh@amd.com>2018-09-14 16:45:58 +0300
committerThomas Gleixner <tglx@linutronix.de>2018-09-15 21:48:45 +0300
commitb3f0907c71e006e12fde74ea9a745b6096b6f90f (patch)
treedb20afaf037c1228abafd1e2b6718f68698f0d35 /arch/x86/mm/init.c
parent27c5a778dfe23d1de8d9ebfbc6a54595a79ac709 (diff)
downloadlinux-b3f0907c71e006e12fde74ea9a745b6096b6f90f.tar.xz
x86/mm: Add .bss..decrypted section to hold shared variables
kvmclock defines few static variables which are shared with the hypervisor during the kvmclock initialization. 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 before sharing it. Currently, we use kernel_physical_mapping_init() to split large pages before clearing the C-bit on shared pages. But it fails when called from the kvmclock initialization (mainly because the memblock allocator is not ready that early during boot). Add a __bss_decrypted section attribute which can be used when defining such shared variable. The so-defined variables will be placed in the .bss..decrypted section. This section will be mapped with C=0 early during boot. The .bss..decrypted section has a big chunk of memory that may be unused when memory encryption is not active, free it when memory encryption is not active. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: Radim Krčmář<rkrcmar@redhat.com> Cc: kvm@vger.kernel.org Link: https://lkml.kernel.org/r/1536932759-12905-2-git-send-email-brijesh.singh@amd.com
Diffstat (limited to 'arch/x86/mm/init.c')
-rw-r--r--arch/x86/mm/init.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 7a8fc26c1115..faca978ebf9d 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -815,10 +815,14 @@ void free_kernel_image_pages(void *begin, void *end)
set_memory_np_noalias(begin_ul, len_pages);
}
+void __weak mem_encrypt_free_decrypted_mem(void) { }
+
void __ref free_initmem(void)
{
e820__reallocate_tables();
+ mem_encrypt_free_decrypted_mem();
+
free_kernel_image_pages(&__init_begin, &__init_end);
}