On 10/12/2015 10:28 PM, James Morse wrote:
On 29/05/15 06:38, AKASHI Takahiro wrote:
The current kvm implementation on arm64 does cpu-specific initialization
at system boot, and has no way to gracefully shutdown a core in terms of
kvm. This prevents, especially, kexec from rebooting the system on a boot
core in EL2.
This patch adds a cpu tear-down function and also puts an existing cpu-init
code into a separate function, kvm_arch_hardware_disable() and
kvm_arch_hardware_enable() respectively.
We don't need arm64-specific cpu hotplug hook any more.
I think we do... on platforms where cpuidle uses psci to temporarily turn
off cores that aren't in use, we lose the el2 state. This hotplug hook
restores the state, even if there a no vms running.
If I understand you correctly, with or without my patch, kvm doesn't work
under cpuidle anyway. Right?
If so, saving/restoring cpu states (or at least, kicking cpu hotplug hooks)
is cpuidle driver's responsibility, isn't it?
-Takahiro AKASHI
This patch prevents me from running vms on such a platform, qemu gives:
kvm [1500]: Unsupported exception type: 6264688KVM internal error.
Suberror: 0
kvmtool goes with a more dramatic:
KVM exit reason: 17 ("KVM_EXIT_INTERNAL_ERROR")
Disabling CONFIG_ARM_CPUIDLE solves this problem.
(Sorry to revive an old thread - I've been using v4 of this patch for the
hibernate/suspend-to-disk series).
Since this patch modifies common part of code between arm and arm64, one
stub definition, __cpu_reset_hyp_mode(), is added on arm side to avoid
compiling errors.
Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org>
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index fd085ec..afe6263 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -1136,6 +1136,11 @@ ENTRY(kvm_call_hyp)
ret
ENDPROC(kvm_call_hyp)
+ENTRY(kvm_call_reset)
+ hvc #HVC_RESET
+ ret
+ENDPROC(kvm_call_reset)
+
.macro invalid_vector label, target
.align 2
\label:
@@ -1179,10 +1184,27 @@ el1_sync: //
Guest trapped into EL2
cmp x18, #HVC_GET_VECTORS
b.ne 1f
mrs x0, vbar_el2
- b 2f
-
-1: /* Default to HVC_CALL_HYP. */
+ b do_eret
+ /* jump into trampoline code */
+1: cmp x18, #HVC_RESET
+ b.ne 2f
+ /*
+ * Entry point is:
+ * TRAMPOLINE_VA
+ * + (__kvm_hyp_reset - (__hyp_idmap_text_start & PAGE_MASK))
+ */
+ adrp x2, __kvm_hyp_reset
+ add x2, x2, #:lo12:__kvm_hyp_reset
+ adrp x3, __hyp_idmap_text_start
+ add x3, x3, #:lo12:__hyp_idmap_text_start
+ and x3, x3, PAGE_MASK
+ sub x2, x2, x3
+ ldr x3, =TRAMPOLINE_VA
+ add x2, x2, x3
+ br x2 // no return
+
+2: /* Default to HVC_CALL_HYP. */
What was the reason not to use kvm_call_hyp(__kvm_hyp_reset, ...)?
(You mentioned you wanted to at [0] - I can't find the details in the archive)
Thanks,
James
[0] http://lists.infradead.org/pipermail/kexec/2015-April/335533.html
push lr, xzr
/*
@@ -1196,7 +1218,9 @@ el1_sync: // Guest
trapped into EL2
blr lr
pop lr, xzr
-2: eret
+
+do_eret:
+ eret
el1_trap:
/*
--
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