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Re: [Qemu-devel] [PATCH] ivshmem: fix guest unable to start with ioevent
From: |
Cam Macdonell |
Subject: |
Re: [Qemu-devel] [PATCH] ivshmem: fix guest unable to start with ioeventfd |
Date: |
Mon, 5 Dec 2011 12:27:47 -0700 |
2011/12/2 Cam Macdonell <address@hidden>:
> 2011/11/30 Cam Macdonell <address@hidden>:
>> 2011/11/30 Zang Hongyong <address@hidden>:
>>> Can this bug fix patch be applied yet?
>>
>> Sorry, for not replying yet. I'll test your patch within the next day.
>
> Have you confirmed the proper receipt of interrupts in the receiving guests?
>
> I can confirm the bug occurs with ioeventfd enabled and that the
> patches fixes it, but sometime after 15.1, I no longer see interrupts
> (MSI or regular) being delivered in the guest.
>
> I will bisect tomorrow.
With Michael's help we debugged msi-x interrupt delivery. With that
fix in place, this patch fixes ioeventfd in ivshmem.
>
> Cam
>
>>
>>> With this bug, guest os cannot successfully boot with ioeventfd.
>>> Thus the new PIO DoorBell patch cannot be posted.
>>
>> Well, you can certainly post the new patch, just clarify that it's
>> dependent on this patch.
>>
>> Sincerely,
>> Cam
>>
>>>
>>> Thanks,
>>> Hongyong
>>>
>>> 于 2011/11/24,星期四 18:05, address@hidden 写道:
>>>> From: Hongyong Zang <address@hidden>
>>>>
>>>> When a guest boots with ioeventfd, an error (by gdb) occurs:
>>>> Program received signal SIGSEGV, Segmentation fault.
>>>> 0x00000000006009cc in setup_ioeventfds (s=0x171dc40)
>>>> at /home/louzhengwei/git_source/qemu-kvm/hw/ivshmem.c:363
>>>> 363 for (j = 0; j < s->peers[i].nb_eventfds; j++) {
>>>> The bug is due to accessing s->peers which is NULL.
>>>>
>>>> This patch uses the memory region API to replace the old one
>>>> kvm_set_ioeventfd_mmio_long().
>>>> And this patch makes memory_region_add_eventfd() called in ivshmem_read()
>>>> when qemu receives
>>>> eventfd information from ivshmem_server.
>>>>
>>>> Signed-off-by: Hongyong Zang <address@hidden>
>>>> ---
>>>> hw/ivshmem.c | 41 ++++++++++++++---------------------------
>>>> 1 files changed, 14 insertions(+), 27 deletions(-)
>>>>
>>>> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
>>>> index 242fbea..be26f03 100644
>>>> --- a/hw/ivshmem.c
>>>> +++ b/hw/ivshmem.c
>>>> @@ -58,7 +58,6 @@ typedef struct IVShmemState {
>>>> CharDriverState *server_chr;
>>>> MemoryRegion ivshmem_mmio;
>>>>
>>>> - pcibus_t mmio_addr;
>>>> /* We might need to register the BAR before we actually have the
>>>> memory.
>>>> * So prepare a container MemoryRegion for the BAR immediately and
>>>> * add a subregion when we have the memory.
>>>> @@ -346,8 +345,14 @@ static void close_guest_eventfds(IVShmemState *s, int
>>>> posn)
>>>> guest_curr_max = s->peers[posn].nb_eventfds;
>>>>
>>>> for (i = 0; i < guest_curr_max; i++) {
>>>> - kvm_set_ioeventfd_mmio_long(s->peers[posn].eventfds[i],
>>>> - s->mmio_addr + DOORBELL, (posn << 16) | i, 0);
>>>> + if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>>>> + memory_region_del_eventfd(&s->ivshmem_mmio,
>>>> + DOORBELL,
>>>> + 4,
>>>> + true,
>>>> + (posn << 16) | i,
>>>> + s->peers[posn].eventfds[i]);
>>>> + }
>>>> close(s->peers[posn].eventfds[i]);
>>>> }
>>>>
>>>> @@ -355,22 +360,6 @@ static void close_guest_eventfds(IVShmemState *s, int
>>>> posn)
>>>> s->peers[posn].nb_eventfds = 0;
>>>> }
>>>>
>>>> -static void setup_ioeventfds(IVShmemState *s) {
>>>> -
>>>> - int i, j;
>>>> -
>>>> - for (i = 0; i <= s->max_peer; i++) {
>>>> - for (j = 0; j < s->peers[i].nb_eventfds; j++) {
>>>> - memory_region_add_eventfd(&s->ivshmem_mmio,
>>>> - DOORBELL,
>>>> - 4,
>>>> - true,
>>>> - (i << 16) | j,
>>>> - s->peers[i].eventfds[j]);
>>>> - }
>>>> - }
>>>> -}
>>>> -
>>>> /* this function increase the dynamic storage need to store data about
>>>> other
>>>> * guests */
>>>> static void increase_dynamic_storage(IVShmemState *s, int new_min_size) {
>>>> @@ -491,10 +480,12 @@ static void ivshmem_read(void *opaque, const uint8_t
>>>> * buf, int flags)
>>>> }
>>>>
>>>> if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>>>> - if (kvm_set_ioeventfd_mmio_long(incoming_fd, s->mmio_addr +
>>>> DOORBELL,
>>>> - (incoming_posn << 16) | guest_max_eventfd, 1) <
>>>> 0) {
>>>> - fprintf(stderr, "ivshmem: ioeventfd not available\n");
>>>> - }
>>>> + memory_region_add_eventfd(&s->ivshmem_mmio,
>>>> + DOORBELL,
>>>> + 4,
>>>> + true,
>>>> + (incoming_posn << 16) |
>>>> guest_max_eventfd,
>>>> + incoming_fd);
>>>> }
>>>>
>>>> return;
>>>> @@ -659,10 +650,6 @@ static int pci_ivshmem_init(PCIDevice *dev)
>>>> memory_region_init_io(&s->ivshmem_mmio, &ivshmem_mmio_ops, s,
>>>> "ivshmem-mmio", IVSHMEM_REG_BAR_SIZE);
>>>>
>>>> - if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>>>> - setup_ioeventfds(s);
>>>> - }
>>>> -
>>>> /* region for registers*/
>>>> pci_register_bar(&s->dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY,
>>>> &s->ivshmem_mmio);
>>>
>>>