diff options
| author | Brijesh Singh <brijesh.singh@amd.com> | 2018-09-14 08:45:58 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-09-15 20:48:45 +0200 |
| commit | b3f0907c71e006e12fde74ea9a745b6096b6f90f (patch) | |
| tree | db20afaf037c1228abafd1e2b6718f68698f0d35 /arch/x86/kernel/head64.c | |
| parent | 27c5a778dfe23d1de8d9ebfbc6a54595a79ac709 (diff) | |
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/kernel/head64.c')
| -rw-r--r-- | arch/x86/kernel/head64.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 8047379e575a..c16af27eb23f 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -112,6 +112,7 @@ static bool __head check_la57_support(unsigned long physaddr) unsigned long __head __startup_64(unsigned long physaddr, struct boot_params *bp) { + unsigned long vaddr, vaddr_end; unsigned long load_delta, *p; unsigned long pgtable_flags; pgdval_t *pgd; @@ -235,6 +236,21 @@ unsigned long __head __startup_64(unsigned long physaddr, sme_encrypt_kernel(bp); /* + * Clear the memory encryption mask from the .bss..decrypted section. + * The bss section will be memset to zero later in the initialization so + * there is no need to zero it after changing the memory encryption + * attribute. + */ + if (mem_encrypt_active()) { + vaddr = (unsigned long)__start_bss_decrypted; + vaddr_end = (unsigned long)__end_bss_decrypted; + for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { + i = pmd_index(vaddr); + pmd[i] -= sme_get_me_mask(); + } + } + + /* * Return the SME encryption mask (if SME is active) to be used as a * modifier for the initial pgdir entry programmed into CR3. */ |