Re: [PATCH v2 1/4] hw/xen: Expose handle_bufioreq in xen_register_ioreq

[Stefano Stabellini]

On Mon, 23 Sep 2024, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>
> 
> Expose handle_bufioreq in xen_register_ioreq().
> This is to allow machines to enable or disable buffered ioreqs.
> 
> No functional change since all callers still set it to
> HVM_IOREQSRV_BUFIOREQ_ATOMIC.
> 
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
>  hw/i386/xen/xen-hvm.c           |   4 +-
>  hw/xen/xen-hvm-common.c         | 101 ++++++++++++++++++++------------
>  hw/xen/xen-pvh-common.c         |   4 +-
>  include/hw/xen/xen-hvm-common.h |   3 +
>  include/hw/xen/xen_native.h     |   3 +-
>  5 files changed, 74 insertions(+), 41 deletions(-)
> 
> diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
> index 4f6446600c..d3df488c48 100644
> --- a/hw/i386/xen/xen-hvm.c
> +++ b/hw/i386/xen/xen-hvm.c
> @@ -614,7 +614,9 @@ void xen_hvm_init_pc(PCMachineState *pcms, MemoryRegion 
> **ram_memory)
>  
>      state = g_new0(XenIOState, 1);
>  
> -    xen_register_ioreq(state, max_cpus, &xen_memory_listener);
> +    xen_register_ioreq(state, max_cpus,
> +                       HVM_IOREQSRV_BUFIOREQ_ATOMIC,
> +                       &xen_memory_listener);
>  
>      xen_is_stubdomain = xen_check_stubdomain(state->xenstore);
>  
> diff --git a/hw/xen/xen-hvm-common.c b/hw/xen/xen-hvm-common.c
> index 3a9d6f981b..3ce994fc3a 100644
> --- a/hw/xen/xen-hvm-common.c
> +++ b/hw/xen/xen-hvm-common.c
> @@ -667,6 +667,8 @@ static int xen_map_ioreq_server(XenIOState *state)
>      xen_pfn_t ioreq_pfn;
>      xen_pfn_t bufioreq_pfn;
>      evtchn_port_t bufioreq_evtchn;
> +    unsigned long num_frames = 1;
> +    unsigned long frame = 1;
>      int rc;
>  
>      /*
> @@ -675,59 +677,79 @@ static int xen_map_ioreq_server(XenIOState *state)
>       */
>      QEMU_BUILD_BUG_ON(XENMEM_resource_ioreq_server_frame_bufioreq != 0);
>      QEMU_BUILD_BUG_ON(XENMEM_resource_ioreq_server_frame_ioreq(0) != 1);
> +
> +    if (state->has_bufioreq) {
> +        frame = 0;
> +        num_frames = 2;
> +    }
>      state->fres = xenforeignmemory_map_resource(xen_fmem, xen_domid,
>                                           XENMEM_resource_ioreq_server,
> -                                         state->ioservid, 0, 2,
> +                                         state->ioservid,
> +                                         frame, num_frames,
>                                           &addr,
>                                           PROT_READ | PROT_WRITE, 0);
>      if (state->fres != NULL) {
>          trace_xen_map_resource_ioreq(state->ioservid, addr);
> -        state->buffered_io_page = addr;
> -        state->shared_page = addr + XC_PAGE_SIZE;
> +        state->shared_page = addr;
> +        if (state->has_bufioreq) {
> +            state->buffered_io_page = addr;
> +            state->shared_page = addr + XC_PAGE_SIZE;
> +        }
>      } else if (errno != EOPNOTSUPP) {
>          error_report("failed to map ioreq server resources: error %d 
> handle=%p",
>                       errno, xen_xc);
>          return -1;
>      }
>  
> -    rc = xen_get_ioreq_server_info(xen_domid, state->ioservid,
> -                                   (state->shared_page == NULL) ?
> -                                   &ioreq_pfn : NULL,
> -                                   (state->buffered_io_page == NULL) ?
> -                                   &bufioreq_pfn : NULL,
> -                                   &bufioreq_evtchn);
> -    if (rc < 0) {
> -        error_report("failed to get ioreq server info: error %d handle=%p",
> -                     errno, xen_xc);
> -        return rc;
> -    }
> -
> -    if (state->shared_page == NULL) {
> +    /*
> +     * If we fail to map the shared page with xenforeignmemory_map_resource()
> +     * or if we're using buffered ioreqs, we need xen_get_ioreq_server_info()
> +     * to provide the the addresses to map the shared page and/or to get the
> +     * event-channel port for buffered ioreqs.
> +     */
> +    if (state->shared_page == NULL || state->has_bufioreq) {
>          trace_xen_map_ioreq_server_shared_page(ioreq_pfn);
> +        rc = xen_get_ioreq_server_info(xen_domid, state->ioservid,
> +                                       (state->shared_page == NULL) ?
> +                                       &ioreq_pfn : NULL,
> +                                       (state->has_bufioreq &&
> +                                        state->buffered_io_page == NULL) ?
> +                                       &bufioreq_pfn : NULL,
> +                                       &bufioreq_evtchn);
> +        if (rc < 0) {
> +            error_report("failed to get ioreq server info: error %d 
> handle=%p",
> +                         errno, xen_xc);
> +            return rc;
> +        }
>  
> -        state->shared_page = xenforeignmemory_map(xen_fmem, xen_domid,
> -                                                  PROT_READ | PROT_WRITE,
> -                                                  1, &ioreq_pfn, NULL);
> +        if (state->shared_page == NULL) {
> +            trace_xen_map_ioreq_server_shared_page(ioreq_pfn);
> +
> +            state->shared_page = xenforeignmemory_map(xen_fmem, xen_domid,
> +                                                      PROT_READ | PROT_WRITE,
> +                                                      1, &ioreq_pfn, NULL);
> +        }
>          if (state->shared_page == NULL) {
>              error_report("map shared IO page returned error %d handle=%p",
>                           errno, xen_xc);
>          }
> -    }
>  
> -    if (state->buffered_io_page == NULL) {
> -        trace_xen_map_ioreq_server_buffered_io_page(bufioreq_pfn);
> +        if (state->has_bufioreq && state->buffered_io_page == NULL) {
> +            trace_xen_map_ioreq_server_buffered_io_page(bufioreq_pfn);
>  
> -        state->buffered_io_page = xenforeignmemory_map(xen_fmem, xen_domid,
> -                                                       PROT_READ | 
> PROT_WRITE,
> -                                                       1, &bufioreq_pfn,
> -                                                       NULL);
> -        if (state->buffered_io_page == NULL) {
> -            error_report("map buffered IO page returned error %d", errno);
> -            return -1;
> +            state->buffered_io_page = xenforeignmemory_map(xen_fmem, 
> xen_domid,
> +                                                        PROT_READ | 
> PROT_WRITE,
> +                                                        1, &bufioreq_pfn,
> +                                                        NULL);
> +            if (state->buffered_io_page == NULL) {
> +                error_report("map buffered IO page returned error %d", 
> errno);
> +                return -1;
> +            }
>          }
>      }
>  
> -    if (state->shared_page == NULL || state->buffered_io_page == NULL) {
> +    if (state->shared_page == NULL ||
> +        (state->has_bufioreq && state->buffered_io_page == NULL)) {
>          return -1;
>      }
>  
> @@ -830,14 +852,15 @@ static void xen_do_ioreq_register(XenIOState *state,
>          state->ioreq_local_port[i] = rc;
>      }
>  
> -    rc = qemu_xen_evtchn_bind_interdomain(state->xce_handle, xen_domid,
> -                                          state->bufioreq_remote_port);
> -    if (rc == -1) {
> -        error_report("buffered evtchn bind error %d", errno);
> -        goto err;
> +    if (state->has_bufioreq) {
> +        rc = qemu_xen_evtchn_bind_interdomain(state->xce_handle, xen_domid,
> +                                              state->bufioreq_remote_port);
> +        if (rc == -1) {
> +            error_report("buffered evtchn bind error %d", errno);
> +            goto err;
> +        }
> +        state->bufioreq_local_port = rc;
>      }
> -    state->bufioreq_local_port = rc;
> -
>      /* Init RAM management */
>  #ifdef XEN_COMPAT_PHYSMAP
>      xen_map_cache_init(xen_phys_offset_to_gaddr, state);
> @@ -865,6 +888,7 @@ err:
>  }
>  
>  void xen_register_ioreq(XenIOState *state, unsigned int max_cpus,
> +                        uint8_t handle_bufioreq,
>                          const MemoryListener *xen_memory_listener)
>  {
>      int rc;
> @@ -883,7 +907,8 @@ void xen_register_ioreq(XenIOState *state, unsigned int 
> max_cpus,
>          goto err;
>      }
>  
> -    rc = xen_create_ioreq_server(xen_domid, &state->ioservid);
> +    state->has_bufioreq = handle_bufioreq != HVM_IOREQSRV_BUFIOREQ_OFF;
> +    rc = xen_create_ioreq_server(xen_domid, handle_bufioreq, 
> &state->ioservid);
>      if (!rc) {
>          xen_do_ioreq_register(state, max_cpus, xen_memory_listener);
>      } else {
> diff --git a/hw/xen/xen-pvh-common.c b/hw/xen/xen-pvh-common.c
> index 28d7168446..08641fdcec 100644
> --- a/hw/xen/xen-pvh-common.c
> +++ b/hw/xen/xen-pvh-common.c
> @@ -194,7 +194,9 @@ static void xen_pvh_init(MachineState *ms)
>      }
>  
>      xen_pvh_init_ram(s, sysmem);
> -    xen_register_ioreq(&s->ioreq, ms->smp.max_cpus, &xen_memory_listener);
> +    xen_register_ioreq(&s->ioreq, ms->smp.max_cpus,
> +                       HVM_IOREQSRV_BUFIOREQ_ATOMIC,
> +                       &xen_memory_listener);
>  
>      if (s->cfg.virtio_mmio_num) {
>          xen_create_virtio_mmio_devices(s);
> diff --git a/include/hw/xen/xen-hvm-common.h b/include/hw/xen/xen-hvm-common.h
> index 3d796235dc..0f586c4384 100644
> --- a/include/hw/xen/xen-hvm-common.h
> +++ b/include/hw/xen/xen-hvm-common.h
> @@ -81,6 +81,8 @@ typedef struct XenIOState {
>      QLIST_HEAD(, XenPciDevice) dev_list;
>      DeviceListener device_listener;
>  
> +    bool has_bufioreq;
> +
>      Notifier exit;
>  } XenIOState;
>  
> @@ -95,6 +97,7 @@ void xen_device_unrealize(DeviceListener *listener, 
> DeviceState *dev);
>  
>  void xen_hvm_change_state_handler(void *opaque, bool running, RunState 
> rstate);
>  void xen_register_ioreq(XenIOState *state, unsigned int max_cpus,
> +                        uint8_t handle_bufioreq,
>                          const MemoryListener *xen_memory_listener);
>  
>  void cpu_ioreq_pio(ioreq_t *req);
> diff --git a/include/hw/xen/xen_native.h b/include/hw/xen/xen_native.h
> index 1a5ad693a4..5caf91a616 100644
> --- a/include/hw/xen/xen_native.h
> +++ b/include/hw/xen/xen_native.h
> @@ -464,10 +464,11 @@ static inline void xen_unmap_pcidev(domid_t dom,
>  }
>  
>  static inline int xen_create_ioreq_server(domid_t dom,
> +                                          int handle_bufioreq,
>                                            ioservid_t *ioservid)
>  {
>      int rc = xendevicemodel_create_ioreq_server(xen_dmod, dom,
> -                                                HVM_IOREQSRV_BUFIOREQ_ATOMIC,
> +                                                handle_bufioreq,
>                                                  ioservid);
>  
>      if (rc == 0) {
> -- 
> 2.43.0
>