On 2021-02-26 18:12, Will Deacon wrote:
Commit 7db21530479f ("KVM: arm64: Restore hyp when panicking in guest
context") tracks the currently running vCPU, clearing the pointer to
NULL on exit from a guest.
Unfortunately, the use of 'set_loaded_vcpu' clobbers x1 to point at the
kvm_hyp_ctxt instead of the vCPU context, causing the subsequent RAS
code to go off into the weeds when it saves the DISR assuming that the
CPU context is embedded in a struct vCPU.
Leave x1 alone and use x3 as a temporary register instead when clearing
the vCPU on the guest exit path.
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Andrew Scull <ascull@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 7db21530479f ("KVM: arm64: Restore hyp when panicking in guest
context")
Suggested-by: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
This was pretty awful to debug!
arch/arm64/kvm/hyp/entry.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index b0afad7a99c6..0c66a1d408fd 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -146,7 +146,7 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// Now restore the hyp regs
restore_callee_saved_regs x2
- set_loaded_vcpu xzr, x1, x2
+ set_loaded_vcpu xzr, x2, x3
alternative_if ARM64_HAS_RAS_EXTN
// If we have the RAS extensions we can consume a pending error
Grmbl... How comes we have never seen that for the past 5 months,
including on CPUs that implement RAS?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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