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Re: [Xen-devel] [PATCH v2 1/1] xen-hvm.c: Add support for Xen access to vmport



On Fri, 3 Oct 2014, Don Slutz wrote:
> On 10/03/14 05:52, Stefano Stabellini wrote:
> > On Thu, 2 Oct 2014, Don Slutz wrote:
> > > 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
> > > 
> > > 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>
> > > ---
> > > v2:
> > >     More info in commit message.
> > >         Added vmware_ioreq_t
> > >        Added cpu_by_ioreq_id.
> > >        Set current_cpu in regs_to_cpu(), clear in regs_from_cpu().
> > >        Drop all changes to vmport.c
> > > 
> > >   xen-hvm.c | 152
> > > +++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
> > >   1 file changed, 137 insertions(+), 15 deletions(-)
> > > 
> > > diff --git a/xen-hvm.c b/xen-hvm.c
> > > index 05e522c..d80f21c 100644
> > > --- a/xen-hvm.c
> > > +++ b/xen-hvm.c
> > > @@ -41,6 +41,31 @@ 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 eax;
> > > +        uint32_t ebx;
> > > +        uint32_t ecx;
> > > +        uint32_t edx;
> > > +        uint32_t vp_eport; /* evtchn for notifications to/from device
> > > model */
> > > +        uint16_t addr;
> > > +        uint8_t  state:4;
> > > +        uint8_t  dir:1;    /* 1=read, 0=write */
> > > +        uint8_t  size:3;
> > > +        uint8_t  type;     /* I/O type */
> > > +};
> > > +typedef struct vmware_ioreq vmware_ioreq_t;
> > > +#endif
> > Why here instead of include/hw/xen/xen_common.h?
> > 
> 
> See code comment above.  Copied here just to make sure.
> 
> +
> +/* 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
> + */

Oh well. OK then.


> > >   #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
> > >   static inline uint32_t xen_vcpu_eport(shared_iopage_t *shared_page, int
> > > i)
> > >   {
> > > @@ -81,6 +106,7 @@ typedef struct XenIOState {
> > >       shared_iopage_t *shared_page;
> > >       buffered_iopage_t *buffered_io_page;
> > >       QEMUTimer *buffered_io_timer;
> > > +    CPUState **cpu_by_ioreq_id;
> > >       /* the evtchn port for polling the notification, */
> > >       evtchn_port_t *ioreq_local_port;
> > >       /* evtchn local port for buffered io */
> > > @@ -101,6 +127,8 @@ 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)
> > > @@ -596,11 +624,23 @@ static ioreq_t
> > > *cpu_get_ioreq_from_shared_memory(XenIOState *state, int vcpu)
> > >       ioreq_t *req = xen_vcpu_ioreq(state->shared_page, vcpu);
> > >         if (req->state != STATE_IOREQ_READY) {
> > > -        DPRINTF("I/O request not ready: "
> > > -                "%x, ptr: %x, port: %"PRIx64", "
> > > -                "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %"
> > > FMT_ioreq_size "\n",
> > > -                req->state, req->data_is_ptr, req->addr,
> > > -                req->data, req->count, req->size);
> > > +        if (req->type != IOREQ_TYPE_VMWARE_PORT) {
> > > +            DPRINTF("I/O request not ready: "
> > > +                    "%x, ptr: %x, port: %"PRIx64", "
> > > +                    "data: %"PRIx64", count: %" FMT_ioreq_size ", size:
> > > %"
> > > +                    FMT_ioreq_size "\n",
> > > +                    req->state, req->data_is_ptr, req->addr,
> > > +                    req->data, req->count, req->size);
> > > +        } else {
> > > +#ifdef DEBUG_XEN_HVM
> > > +            vmware_ioreq_t *vp = (vmware_ioreq_t *)req;
> > > +            DPRINTF("I/O VMware request not ready: "
> > > +                    "%x, ptr: 0, port: %x, data: %x"
> > > +                    ", count: 1, size: %d\n",
> > > +                    vp->state, (uint16_t)vp->edx, vp->eax,
> > > +                    vp->size);
> > > +#endif
> > > +        }
> > >           return NULL;
> > >       }
> > >   @@ -773,10 +813,73 @@ 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)
> > > +{
> > > +    X86CPU *cpu;
> > > +    CPUX86State *env;
> > > +
> > > +    if (!state->cpu_by_ioreq_id[0]) {
> > > +        CPUState *cpu_state;
> > > +
> > > +        CPU_FOREACH(cpu_state) {
> > > +            state->cpu_by_ioreq_id[cpu_state->cpu_index] = cpu_state;
> > > +        }
> > > +    }
> > This is just the initialization, isn't it?
> > It would be best to move it to an initialization function then.
> > 
> 
> A new initialization function would need to be added.  A new call to it would
> need
> to be added (not sure where the best place is).  Since the overhead here is
> small I went with the less intrusive change.

I'd prefer the initialization function if it is possible.


> > > +    current_cpu = state->cpu_by_ioreq_id[state->send_vcpu];
> > > +    cpu = X86_CPU(current_cpu);
> > > +    env = &cpu->env;
> > > +    env->regs[R_EAX] = vmport_req->eax;
> > > +    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));
> > > +    assert(offsetof(ioreq_t, type) == offsetof(vmware_ioreq_t, type));
> > > +    assert(offsetof(ioreq_t, vp_eport) == offsetof(vmware_ioreq_t,
> > > vp_eport));
> > > +
> > > +    vmport_req->eax = env->regs[R_EAX];
> > > +    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, vmware_ioreq_t
> > > *vmport_req)
> > > +{
> > > +    ioreq_t req;
> > > +
> > > +    memset(&req, 0x00, sizeof(req));
> > > +
> > > +    req.size = vmport_req->size;
> > > +    req.count = 1;
> > > +    req.addr = vmport_req->addr;
> > > +    req.data = vmport_req->eax;
> > > +    req.state = STATE_IOREQ_READY;
> > > +    req.dir = vmport_req->dir;
> > > +    req.df = 0;
> > > +    req.type = IOREQ_TYPE_PIO;
> > > +    req.data_is_ptr = 0;
> > > +
> > > +    regs_to_cpu(state, vmport_req);
> > > +    handle_ioreq(state, &req);
> > > +    regs_from_cpu(state, vmport_req, &req);
> > > +}
> > I think that this is far better than the previous version
> >         
> 
> Good.
> 
>    -Don Slutz
> 
> 

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