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Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume o
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations |
Date: |
Wed, 26 Jan 2011 09:14:37 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-01-25 17:49, Stefan Berger wrote:
> On 01/25/2011 02:26 AM, Jan Kiszka wrote:
>>
>> Do you see a chance to look closer at the issue yourself? E.g.
>> instrument the kernel's irqchip models and dump their states once your
>> guest is stuck?
> The device runs on iRQ 3. So I applied this patch here.
>
> diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
> index 3cece05..8f4f94c 100644
> --- a/arch/x86/kvm/i8259.c
> +++ b/arch/x86/kvm/i8259.c
> @@ -106,7 +106,7 @@ static inline int pic_set_irq1(struct kvm_kpic_state
> *s, int irq, int level)
> {
> int mask, ret = 1;
> mask = 1<< irq;
> - if (s->elcr& mask) /* level triggered */
> + if (s->elcr& mask) /* level triggered */ {
> if (level) {
> ret = !(s->irr& mask);
> s->irr |= mask;
> @@ -115,7 +115,10 @@ static inline int pic_set_irq1(struct
> kvm_kpic_state *s, int irq, int level)
> s->irr&= ~mask;
> s->last_irr&= ~mask;
> }
> - else /* edge triggered */
> +if (irq == 3)
> + printk("%s %d: level=%d, irr = %x\n", __FUNCTION__,__LINE__,level,
> s->irr);
> + }
> + else /* edge triggered */ {
> if (level) {
> if ((s->last_irr& mask) == 0) {
> ret = !(s->irr& mask);
> @@ -124,7 +127,9 @@ static inline int pic_set_irq1(struct kvm_kpic_state
> *s, int irq, int level)
> s->last_irr |= mask;
> } else
> s->last_irr&= ~mask;
> -
> +if (irq == 3)
> + printk("%s %d: level=%d, irr = %x\n", __FUNCTION__,__LINE__,level,
> s->irr);
> + }
> return (s->imr& mask) ? -1 : ret;
> }
>
> @@ -206,6 +211,8 @@ int kvm_pic_set_irq(void *opaque, int irq, int level)
>
> pic_lock(s);
> if (irq>= 0&& irq< PIC_NUM_PINS) {
> +if (irq == 3)
> +printk("%s\n", __FUNCTION__);
> ret = pic_set_irq1(&s->pics[irq>> 3], irq& 7, level);
> pic_update_irq(s);
> trace_kvm_pic_set_irq(irq>> 3, irq& 7, s->pics[irq>> 3].elcr,
>
>
>
> While it's still working I see this here with the levels changing 0-1-0.
> Though then it stops and levels are only at '1'.
>
> [ 1773.833824] kvm_pic_set_irq
> [ 1773.833827] pic_set_irq1 131: level=0, irr = 5b
> [ 1773.834161] kvm_pic_set_irq
> [ 1773.834163] pic_set_irq1 131: level=1, irr = 5b
> [ 1773.834193] kvm_pic_set_irq
> [ 1773.834195] pic_set_irq1 131: level=0, irr = 5b
> [ 1773.835028] kvm_pic_set_irq
> [ 1773.835031] pic_set_irq1 131: level=1, irr = 5b
> [ 1773.835542] kvm_pic_set_irq
> [ 1773.835545] pic_set_irq1 131: level=1, irr = 5b
> [ 1773.889892] kvm_pic_set_irq
> [ 1773.889894] pic_set_irq1 131: level=1, irr = 5b
> [ 1791.258793] pic_set_irq1 119: level=1, irr = d9
> [ 1791.258824] pic_set_irq1 119: level=0, irr = d1
> [ 1791.402476] pic_set_irq1 119: level=1, irr = d9
> [ 1791.402534] pic_set_irq1 119: level=0, irr = d1
> [ 1791.402538] pic_set_irq1 119: level=1, irr = d9
> [...]
>
>
> I believe the last 5 shown calls can be ignored. After that the
> interrupts don't go through anymore.
>
> In the device model I see interrupts being raised and cleared. After the
> last one was cleared in 'my' device model, only interrupts are raised.
> This looks like as if the interrupt handler in the guest Linux was never
> run, thus the IRQ is never cleared and we're stuck.
>
User space is responsible for both setting and clearing that line. IRQ3
means you are using some serial device model? Then you should check what
its state is.
Moreover, a complete picture of the kernel/user space interaction should
be obtainable by using fstrace for capturing kvm events.
Jan
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- [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/17
- [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Jan Kiszka, 2011/01/18
- [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/24
- [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Jan Kiszka, 2011/01/24
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/24
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Jan Kiszka, 2011/01/25
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/25
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations,
Jan Kiszka <=
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/26
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Jan Kiszka, 2011/01/26
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/26
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Jan Kiszka, 2011/01/26
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Jan Kiszka, 2011/01/26
- Re: [Qemu-devel] Re: Errors on MMIO read access on VM suspend / resume operations, Stefan Berger, 2011/01/26