From 5d994374e872bef1bba25c80950af6a77ea470e1 Mon Sep 17 00:00:00 2001 From: James Morse Date: Tue, 18 Jun 2019 16:17:35 +0100 Subject: [PATCH] KVM: arm64: Make indirect vectors preamble behaviour symmetric The KVM indirect vectors support is a little complicated. Different CPUs may use different exception vectors for KVM that are generated at boot. Adding new instructions involves checking all the possible combinations do the right thing. To make changes here easier to review lets state what we expect of the preamble: 1. The first vector run, must always run the preamble. 2. Patching the head or tail of the vector shouldn't remove preamble instructions. Today, this is easy as we only have one instruction in the preamble. Change the unpatched tail of the indirect vector so that it always runs this, regardless of patching. Signed-off-by: James Morse Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/hyp-entry.S | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index 318a2f3..a911b8f 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -275,7 +275,7 @@ ENDPROC(__kvm_hyp_vector) /* * The default sequence is to directly branch to the KVM vectors, * using the computed offset. This applies for VHE as well as - * !ARM64_HARDEN_EL2_VECTORS. + * !ARM64_HARDEN_EL2_VECTORS. The first vector must always run the preamble. * * For ARM64_HARDEN_EL2_VECTORS configurations, this gets replaced * with: @@ -291,8 +291,8 @@ ENDPROC(__kvm_hyp_vector) * See kvm_patch_vector_branch for details. */ alternative_cb kvm_patch_vector_branch - b __kvm_hyp_vector + (1b - 0b) - nop + stp x0, x1, [sp, #-16]! + b __kvm_hyp_vector + (1b - 0b + KVM_VECTOR_PREAMBLE) nop nop nop -- 2.7.4