Re: [Xen-devel] [PATCH v4 1/1] xen-hvm.c: Add support for Xen access to vmport

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Don Slutz [mailto:dslutz@xxxxxxxxxxx]
> Sent: 17 October 2014 13:14
> To: qemu-devel@xxxxxxxxxx; Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Alexander Graf; Andreas Färber;
> Anthony Liguori; Don Slutz; Marcel Apfelbaum; Markus Armbruster; Michael
> S. Tsirkin; Stefano Stabellini
> Subject: [PATCH v4 1/1] xen-hvm.c: Add support for Xen access to vmport
> 
> This adds synchronisation of the 6 vcpu registers (only 32bits of
> them) that vmport.c needs between Xen and QEMU.
> 
> This is to avoid a 2nd and 3rd exchange between QEMU and Xen to
> fetch and put these 6 vcpu registers used by the code in vmport.c
> and vmmouse.c
> 
> The registers are passed in the new shared page provided by
> HVM_PARAM_VMPORT_IOREQ_PFN.
> 
> Add new array to XenIOState that allows selection of current_cpu by
> ioreq_id.
> 
> Now pass XenIOState to handle_ioreq().
> 
> Add new routines regs_to_cpu(), regs_from_cpu(), and
> handle_vmport_ioreq().
> 
> Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>
> ---
>  include/hw/xen/xen_common.h |  15 ++++++
>  xen-hvm.c                   | 121
> ++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 131 insertions(+), 5 deletions(-)
> 
> diff --git a/include/hw/xen/xen_common.h
> b/include/hw/xen/xen_common.h
> index 07731b9..9542756 100644
> --- a/include/hw/xen/xen_common.h
> +++ b/include/hw/xen/xen_common.h
> @@ -164,4 +164,19 @@ void destroy_hvm_domain(bool reboot);
>  /* shutdown/destroy current domain because of an error */
>  void xen_shutdown_fatal_error(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
> 
> +#ifdef HVM_PARAM_VMPORT_IOREQ_PFN
> +static inline int xen_get_vmport_ioreq_pfn(XenXC xc, domid_t dom,
> +                                           unsigned long *vmport_ioreq_pfn)
> +{
> +    return xc_get_hvm_param(xc, dom,
> HVM_PARAM_VMPORT_IOREQ_PFN,
> +                            vmport_ioreq_pfn);
> +}
> +#else
> +static inline int xen_get_vmport_ioreq_pfn(XenXC xc, domid_t dom,
> +                                           unsigned long *vmport_ioreq_pfn)
> +{
> +    return -ENOSYS;
> +}
> +#endif
> +
>  #endif /* QEMU_HW_XEN_COMMON_H */
> diff --git a/xen-hvm.c b/xen-hvm.c
> index 05e522c..17b3cbd 100644
> --- a/xen-hvm.c
> +++ b/xen-hvm.c
> @@ -41,6 +41,29 @@ static MemoryRegion *framebuffer;
>  static bool xen_in_migration;
> 
>  /* Compatibility with older version */
> +
> +/* This allows QEMU to build on a system that has Xen 4.5 or earlier
> + * installed.  This here (not in hw/xen/xen_common.h) because
> xen/hvm/ioreq.h
> + * needs to be included before this block and hw/xen/xen_common.h
> needs to
> + * be included before xen/hvm/ioreq.h
> + */
> +#ifndef IOREQ_TYPE_VMWARE_PORT
> +#define IOREQ_TYPE_VMWARE_PORT  3
> +struct vmware_ioreq {
> +    uint32_t esi;
> +    uint32_t edi;
> +    uint32_t ebx;
> +    uint32_t ecx;
> +    uint32_t edx;
> +};
> +typedef struct vmware_ioreq vmware_ioreq_t;

This struct is not really a request any more. Maybe vmware_regs_t?

> +
> +struct shared_vmport_iopage {
> +    struct vmware_ioreq vcpu_vmport_ioreq[1];
> +};
> +typedef struct shared_vmport_iopage shared_vmport_iopage_t;
> +#endif
> +
>  #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
>  static inline uint32_t xen_vcpu_eport(shared_iopage_t *shared_page, int i)
>  {
> @@ -79,8 +102,10 @@ typedef struct XenPhysmap {
> 
>  typedef struct XenIOState {
>      shared_iopage_t *shared_page;
> +    shared_vmport_iopage_t *shared_vmport_page;
>      buffered_iopage_t *buffered_io_page;
>      QEMUTimer *buffered_io_timer;
> +    CPUState **cpu_by_ioreq_id;

This name implies the array is indexed by an id carries in the ioreq. That 
doesn't seem to be the case; it's just indexed by guest vcpu id isn't it?

>      /* the evtchn port for polling the notification, */
>      evtchn_port_t *ioreq_local_port;
>      /* evtchn local port for buffered io */
> @@ -101,6 +126,8 @@ typedef struct XenIOState {
>      Notifier wakeup;
>  } XenIOState;
> 
> +static void handle_ioreq(XenIOState *state, ioreq_t *req);
> +
>  /* Xen specific function for piix pci */
> 
>  int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
> @@ -610,6 +637,20 @@ static ioreq_t
> *cpu_get_ioreq_from_shared_memory(XenIOState *state, int vcpu)
>      return req;
>  }
> 
> +/* get the vmport ioreq packets from share mem */
> +static vmware_ioreq_t *cpu_get_vmport_ioreq_from_shared_memory(

Is this worth its own function? I can only see one use of it in 
handle_vmport_ioreq below...

> +    XenIOState *state, int vcpu)
> +{
> +    vmware_ioreq_t *vmport_req;
> +
> +    assert(state->shared_vmport_page);
> +    vmport_req = &state->shared_vmport_page-
> >vcpu_vmport_ioreq[vcpu];
> +
> +    xen_rmb(); /* see IOREQ_READY /then/ read contents of ioreq */

I don't think that comment is applicable here, and I don't think you need the 
barrier anyway.

> +
> +    return vmport_req;
> +}
> +
>  /* use poll to get the port notification */
>  /* ioreq_vec--out,the */
>  /* retval--the number of ioreq packet */
> @@ -773,7 +814,50 @@ static void cpu_ioreq_move(ioreq_t *req)
>      }
>  }
> 
> -static void handle_ioreq(ioreq_t *req)
> +static void regs_to_cpu(XenIOState *state, vmware_ioreq_t *vmport_req,
> +                        ioreq_t *req)
> +{
> +    X86CPU *cpu;
> +    CPUX86State *env;
> +
> +    current_cpu = state->cpu_by_ioreq_id[state->send_vcpu];
> +    cpu = X86_CPU(current_cpu);
> +    env = &cpu->env;
> +    env->regs[R_EAX] = req->data;
> +    env->regs[R_EBX] = vmport_req->ebx;
> +    env->regs[R_ECX] = vmport_req->ecx;
> +    env->regs[R_EDX] = vmport_req->edx;
> +    env->regs[R_ESI] = vmport_req->esi;
> +    env->regs[R_EDI] = vmport_req->edi;
> +}
> +
> +static void regs_from_cpu(XenIOState *state, vmware_ioreq_t
> *vmport_req,
> +                          ioreq_t *req)
> +{
> +    X86CPU *cpu = X86_CPU(current_cpu);
> +    CPUX86State *env = &cpu->env;
> +
> +    assert(sizeof(*vmport_req) <= sizeof(*req));

Why?

> +
> +    vmport_req->ebx = env->regs[R_EBX];
> +    vmport_req->ecx = env->regs[R_ECX];
> +    vmport_req->edx = env->regs[R_EDX];
> +    vmport_req->esi = env->regs[R_ESI];
> +    vmport_req->edi = env->regs[R_EDI];
> +    current_cpu = NULL;
> +}
> +
> +static void handle_vmport_ioreq(XenIOState *state, ioreq_t *req)
> +{
> +    vmware_ioreq_t *vmport_req =
> +        cpu_get_vmport_ioreq_from_shared_memory(state, state-
> >send_vcpu);
> +
> +    regs_to_cpu(state, vmport_req, req);
> +    cpu_ioreq_pio(req);
> +    regs_from_cpu(state, vmport_req, req);

state appears to be unused in this function, and you could avoid passing it to 
both of them by setting current_cpu here couldn't you?

  Paul

> +}
> +
> +static void handle_ioreq(XenIOState *state, ioreq_t *req)
>  {
>      if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) &&
>              (req->size < sizeof (target_ulong))) {
> @@ -787,6 +871,9 @@ static void handle_ioreq(ioreq_t *req)
>          case IOREQ_TYPE_COPY:
>              cpu_ioreq_move(req);
>              break;
> +        case IOREQ_TYPE_VMWARE_PORT:
> +            handle_vmport_ioreq(state, req);
> +            break;
>          case IOREQ_TYPE_TIMEOFFSET:
>              break;
>          case IOREQ_TYPE_INVALIDATE:
> @@ -828,7 +915,7 @@ static int handle_buffered_iopage(XenIOState
> *state)
>              req.data |= ((uint64_t)buf_req->data) << 32;
>          }
> 
> -        handle_ioreq(&req);
> +        handle_ioreq(state, &req);
> 
>          xen_mb();
>          state->buffered_io_page->read_pointer += qw ? 2 : 1;
> @@ -857,14 +944,16 @@ static void cpu_handle_ioreq(void *opaque)
> 
>      handle_buffered_iopage(state);
>      if (req) {
> -        handle_ioreq(req);
> +        handle_ioreq(state, req);
> 
>          if (req->state != STATE_IOREQ_INPROCESS) {
>              fprintf(stderr, "Badness in I/O request ... not in service?!: "
>                      "%x, ptr: %x, port: %"PRIx64", "
> -                    "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %"
> FMT_ioreq_size "\n",
> +                    "data: %"PRIx64", count: %" FMT_ioreq_size
> +                    ", size: %" FMT_ioreq_size
> +                    ", type: %"FMT_ioreq_size"\n",
>                      req->state, req->data_is_ptr, req->addr,
> -                    req->data, req->count, req->size);
> +                    req->data, req->count, req->size, req->type);
>              destroy_hvm_domain(false);
>              return;
>          }
> @@ -904,6 +993,14 @@ static void xen_main_loop_prepare(XenIOState
> *state)
>                                                   state);
> 
>      if (evtchn_fd != -1) {
> +        CPUState *cpu_state;
> +
> +        DPRINTF("%s: Init cpu_by_ioreq_id\n", __func__);
> +        CPU_FOREACH(cpu_state) {
> +            DPRINTF("%s: cpu_by_ioreq_id[%d]=%p\n",
> +                    __func__, cpu_state->cpu_index, cpu_state);
> +            state->cpu_by_ioreq_id[cpu_state->cpu_index] = cpu_state;
> +        }
>          qemu_set_fd_handler(evtchn_fd, cpu_handle_ioreq, NULL, state);
>      }
>  }
> @@ -1020,6 +1117,17 @@ int xen_hvm_init(ram_addr_t
> *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
>                   errno, xen_xc);
>      }
> 
> +    if (!xen_get_vmport_ioreq_pfn(xen_xc, xen_domid, &ioreq_pfn)) {
> +        DPRINTF("shared vmport page at pfn %lx\n", ioreq_pfn);
> +        state->shared_vmport_page =
> +            xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
> +                                 PROT_READ|PROT_WRITE, ioreq_pfn);
> +        if (state->shared_vmport_page == NULL) {
> +            hw_error("map shared vmport IO page returned error %d handle="
> +                     XC_INTERFACE_FMT, errno, xen_xc);
> +        }
> +    }
> +
>      xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_PFN,
> &ioreq_pfn);
>      DPRINTF("buffered io page at pfn %lx\n", ioreq_pfn);
>      state->buffered_io_page = xc_map_foreign_range(xen_xc, xen_domid,
> XC_PAGE_SIZE,
> @@ -1028,6 +1136,9 @@ int xen_hvm_init(ram_addr_t
> *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
>          hw_error("map buffered IO page returned error %d", errno);
>      }
> 
> +    /* Note: cpus is empty at this point in init */
> +    state->cpu_by_ioreq_id = g_malloc0(max_cpus * sizeof(CPUState *));
> +
>      state->ioreq_local_port = g_malloc0(max_cpus * sizeof (evtchn_port_t));
> 
>      /* FIXME: how about if we overflow the page here? */
> --
> 1.8.4


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