xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: arm64: Abstract the size of the HYP vectors pre-amble

Browse Source 
The EL2 vector hardening feature causes KVM to generate vectors for
each type of CPU present in the system. The generated sequences already
do some of the early guest-exit work (i.e. saving registers). To avoid
duplication the generated vectors branch to the original vector just
after the preamble. This size is hard coded.

Adding new instructions to the HYP vector causes strange side effects,
which are difficult to debug as the affected code is patched in at
runtime.

Add KVM_VECTOR_PREAMBLE to tell kvm_patch_vector_branch() how big
the preamble is. The valid_vect macro can then validate this at
build time.

Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
James Morse
2019-06-18 16:17:34 +01:00
committed by Marc Zyngier
parent 2b68a2a963
commit 3dbf100b0b
3 changed files with 26 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
arch/arm64/kvm/va_layout.c
View File

@@ -170,11 +170,10 @@ void kvm_patch_vector_branch(struct alt_instr *alt,
addr |= ((u64)origptr & GENMASK_ULL(10, 7));
/*
* Branch to the second instruction in the vectors in order to
* avoid the initial store on the stack (which we already
* perform in the hardening vectors).
* Branch over the preamble in order to avoid the initial store on
* the stack (which we already perform in the hardening vectors).
*/
addr += AARCH64_INSN_SIZE;
addr += KVM_VECTOR_PREAMBLE;
/* stp x0, x1, [sp, #-16]! */
insn = aarch64_insn_gen_load_store_pair(AARCH64_INSN_REG_0,