Re: [Qemu-devel] [PATCH v2 07/13] spapr/xive: fix migration of the XiveTCTX under TCG
On 2/26/19 2:02 AM, David Gibson wrote:
> On Fri, Feb 22, 2019 at 02:13:16PM +0100, Cédric Le Goater wrote:
>> When the thread interrupt management state is retrieved from the KVM
>> VCPU, word2 is saved under the QEMU XIVE thread context to print out
>> the OS CAM line under the QEMU monitor.
>>
>> This breaks the migration of a TCG guest (and with KVM when
>> kernel_irqchip=off) because the matching algorithm of the presenter
>> relies on the OS CAM value. Fix with an extra reset of the thread
>> contexts to restore the expected value.
>>
>> Signed-off-by: Cédric Le Goater
>
> As noted elsewhere, I'm not sure this is the right approach to fixing
> this. In any case this can be folded into the previous patch.
I have proposed an alternative in a response to :
[PATCH v2 04/13] spapr/xive: add state synchronization with KVM
C.
>
>> ---
>> hw/ppc/spapr_irq.c | 26 +-
>> 1 file changed, 25 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
>> index 12ecca6264f3..3176098b9f7c 100644
>> --- a/hw/ppc/spapr_irq.c
>> +++ b/hw/ppc/spapr_irq.c
>> @@ -356,7 +356,31 @@ static void
>> spapr_irq_cpu_intc_create_xive(sPAPRMachineState *spapr,
>>
>> static int spapr_irq_post_load_xive(sPAPRMachineState *spapr, int
>> version_id)
>> {
>> -return spapr_xive_post_load(spapr->xive, version_id);
>> +CPUState *cs;
>> +int ret;
>> +
>> +ret = spapr_xive_post_load(spapr->xive, version_id);
>> +if (ret) {
>> +return ret;
>> +}
>> +
>> +/*
>> + * When the states are collected from the KVM XIVE device, word2
>> + * of the XiveTCTX is set to print out the OS CAM line under the
>> + * QEMU monitor.
>> + *
>> + * This breaks the migration on a TCG guest (or on KVM with
>> + * kernel_irqchip=off) because the matching algorithm of the
>> + * presenter relies on the OS CAM value. Fix with an extra reset
>> + * of the thread contexts to restore the expected value.
>> + */
>> +CPU_FOREACH(cs) {
>> +PowerPCCPU *cpu = POWERPC_CPU(cs);
>> +
>> +/* (TCG) Set the OS CAM line of the thread interrupt context. */
>> +spapr_xive_set_tctx_os_cam(spapr_cpu_state(cpu)->tctx);
>> +}
>> +return 0;
>> }
>>
>> static void spapr_irq_reset_xive(sPAPRMachineState *spapr, Error **errp)
>
Re: [Qemu-devel] [PATCH v2 07/13] spapr/xive: fix migration of the XiveTCTX under TCG
On Fri, Feb 22, 2019 at 02:13:16PM +0100, Cédric Le Goater wrote:
> When the thread interrupt management state is retrieved from the KVM
> VCPU, word2 is saved under the QEMU XIVE thread context to print out
> the OS CAM line under the QEMU monitor.
>
> This breaks the migration of a TCG guest (and with KVM when
> kernel_irqchip=off) because the matching algorithm of the presenter
> relies on the OS CAM value. Fix with an extra reset of the thread
> contexts to restore the expected value.
>
> Signed-off-by: Cédric Le Goater
As noted elsewhere, I'm not sure this is the right approach to fixing
this. In any case this can be folded into the previous patch.
> ---
> hw/ppc/spapr_irq.c | 26 +-
> 1 file changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
> index 12ecca6264f3..3176098b9f7c 100644
> --- a/hw/ppc/spapr_irq.c
> +++ b/hw/ppc/spapr_irq.c
> @@ -356,7 +356,31 @@ static void
> spapr_irq_cpu_intc_create_xive(sPAPRMachineState *spapr,
>
> static int spapr_irq_post_load_xive(sPAPRMachineState *spapr, int version_id)
> {
> -return spapr_xive_post_load(spapr->xive, version_id);
> +CPUState *cs;
> +int ret;
> +
> +ret = spapr_xive_post_load(spapr->xive, version_id);
> +if (ret) {
> +return ret;
> +}
> +
> +/*
> + * When the states are collected from the KVM XIVE device, word2
> + * of the XiveTCTX is set to print out the OS CAM line under the
> + * QEMU monitor.
> + *
> + * This breaks the migration on a TCG guest (or on KVM with
> + * kernel_irqchip=off) because the matching algorithm of the
> + * presenter relies on the OS CAM value. Fix with an extra reset
> + * of the thread contexts to restore the expected value.
> + */
> +CPU_FOREACH(cs) {
> +PowerPCCPU *cpu = POWERPC_CPU(cs);
> +
> +/* (TCG) Set the OS CAM line of the thread interrupt context. */
> +spapr_xive_set_tctx_os_cam(spapr_cpu_state(cpu)->tctx);
> +}
> +return 0;
> }
>
> static void spapr_irq_reset_xive(sPAPRMachineState *spapr, Error **errp)
--
David Gibson| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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[Qemu-devel] [PATCH v2 07/13] spapr/xive: fix migration of the XiveTCTX under TCG
When the thread interrupt management state is retrieved from the KVM
VCPU, word2 is saved under the QEMU XIVE thread context to print out
the OS CAM line under the QEMU monitor.
This breaks the migration of a TCG guest (and with KVM when
kernel_irqchip=off) because the matching algorithm of the presenter
relies on the OS CAM value. Fix with an extra reset of the thread
contexts to restore the expected value.
Signed-off-by: Cédric Le Goater
---
hw/ppc/spapr_irq.c | 26 +-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
index 12ecca6264f3..3176098b9f7c 100644
--- a/hw/ppc/spapr_irq.c
+++ b/hw/ppc/spapr_irq.c
@@ -356,7 +356,31 @@ static void
spapr_irq_cpu_intc_create_xive(sPAPRMachineState *spapr,
static int spapr_irq_post_load_xive(sPAPRMachineState *spapr, int version_id)
{
-return spapr_xive_post_load(spapr->xive, version_id);
+CPUState *cs;
+int ret;
+
+ret = spapr_xive_post_load(spapr->xive, version_id);
+if (ret) {
+return ret;
+}
+
+/*
+ * When the states are collected from the KVM XIVE device, word2
+ * of the XiveTCTX is set to print out the OS CAM line under the
+ * QEMU monitor.
+ *
+ * This breaks the migration on a TCG guest (or on KVM with
+ * kernel_irqchip=off) because the matching algorithm of the
+ * presenter relies on the OS CAM value. Fix with an extra reset
+ * of the thread contexts to restore the expected value.
+ */
+CPU_FOREACH(cs) {
+PowerPCCPU *cpu = POWERPC_CPU(cs);
+
+/* (TCG) Set the OS CAM line of the thread interrupt context. */
+spapr_xive_set_tctx_os_cam(spapr_cpu_state(cpu)->tctx);
+}
+return 0;
}
static void spapr_irq_reset_xive(sPAPRMachineState *spapr, Error **errp)
--
2.20.1
