Re: [Qemu-devel] [PATCH v6 1/1] xen-hvm.c: Add support for Xen access to vmport

[Don Slutz <dslutz@verizon.com>]

On 10/20/14 11:03, Stefano Stabellini wrote:
> On Mon, 20 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
>>
>> The registers are passed in the new shared page provided by
>> HVM_PARAM_VMPORT_REGS_PFN.
>>
>> Add new array to XenIOState that allows selection of current_cpu by
>> vcpu 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@verizon.com>
>> Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
>> ---
>> v6:
>>      Do we need a forward declaration?
>>        Nope. Drooped.
>>      Added Reviewed-by from Paul Durrant.
>>
>> v5:
>>      vmware_ioreq_t struct is not really a request any more. Maybe
>>      vmware_regs_t?
>>        Renamed various parts from vmware_ioreq to vmware_regs.  Also
>>        HVM_PARAM_VMPORT_IOREQ_PFN to HVM_PARAM_VMPORT_REGS_PFN.
>>      cpu_by_ioreq_id name implies the array is indexed by an id
>>      carries in the ioreq.
>>        Renamed cpu_by_ioreq_id to cpu_by_vcpu_id.
>>      Is cpu_get_vmport_ioreq_from_shared_memory worth its own
>>      function?
>>        Moved in-line.
>>      I don't think you need the barrier anyway.
>>        Dropped the barrier.
>>      Oh, I now realize you mean the same theoretical rather than
>>      actual limit, in which case this can be a build time check
>>      anyway.
>>        Switch to build time check, move to a better place.
>>      You could avoid passing state to both of them by setting
>>      current_cpu here couldn't you?
>>        Yes, moved state usage to handle_vmport_ioreq().
>>      Error out if it fails with error != -ENOSYS.
>>        Done.
>>
>> v4:
>>      Please try to get rid of the #ifdefs.
>>        Moved 2 #ifdefs into hw/xen/xen_common.h
>>
>>
>>   include/hw/xen/xen_common.h |  22 +++++++++
>>   xen-hvm.c                   | 108 ++++++++++++++++++++++++++++++++++++++++++--
>>   2 files changed, 125 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
>> index 07731b9..42e3d77 100644
>> --- a/include/hw/xen/xen_common.h
>> +++ b/include/hw/xen/xen_common.h
>> @@ -164,4 +164,26 @@ 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_REGS_PFN
>> +static inline int xen_get_vmport_regs_pfn(XenXC xc, domid_t dom,
>> +                                          unsigned long *vmport_regs_pfn)
>> +{
>> +    return xc_get_hvm_param(xc, dom, HVM_PARAM_VMPORT_REGS_PFN,
>> +                            vmport_regs_pfn);
>> +}
>> +#else
>> +static inline int xen_get_vmport_regs_pfn(XenXC xc, domid_t dom,
>> +                                          unsigned long *vmport_regs_pfn)
>> +{
>> +    return -ENOSYS;
>> +}
>> +#endif
>> +
>> +#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
>> +/* Force a compilation error if condition is true */
>> +#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); })
>> +#else
>> +#define BUILD_BUG_ON(cond) ((void)sizeof(struct { int:-!!(cond); }))
>> +#endif
> Use QEMU_BUILD_BUG_ON, please do not define your own. But aside from
> this, it is OK for me.
>

Sigh, I looked for this and failed to find it.  Will switch.
v7 soon.

     -Don Slutz

>>   #endif /* QEMU_HW_XEN_COMMON_H */
>> diff --git a/xen-hvm.c b/xen-hvm.c
>> index 05e522c..7c6291a 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_regs {
>> +    uint32_t esi;
>> +    uint32_t edi;
>> +    uint32_t ebx;
>> +    uint32_t ecx;
>> +    uint32_t edx;
>> +};
>> +typedef struct vmware_regs vmware_regs_t;
>> +
>> +struct shared_vmport_iopage {
>> +    struct vmware_regs vcpu_vmport_regs[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_vcpu_id;
>>       /* the evtchn port for polling the notification, */
>>       evtchn_port_t *ioreq_local_port;
>>       /* evtchn local port for buffered io */
>> @@ -773,7 +798,50 @@ static void cpu_ioreq_move(ioreq_t *req)
>>       }
>>   }
>>   
>> -static void handle_ioreq(ioreq_t *req)
>> +static void regs_to_cpu(vmware_regs_t *vmport_regs, ioreq_t *req)
>> +{
>> +    X86CPU *cpu;
>> +    CPUX86State *env;
>> +
>> +    cpu = X86_CPU(current_cpu);
>> +    env = &cpu->env;
>> +    env->regs[R_EAX] = req->data;
>> +    env->regs[R_EBX] = vmport_regs->ebx;
>> +    env->regs[R_ECX] = vmport_regs->ecx;
>> +    env->regs[R_EDX] = vmport_regs->edx;
>> +    env->regs[R_ESI] = vmport_regs->esi;
>> +    env->regs[R_EDI] = vmport_regs->edi;
>> +}
>> +
>> +static void regs_from_cpu(vmware_regs_t *vmport_regs)
>> +{
>> +    X86CPU *cpu = X86_CPU(current_cpu);
>> +    CPUX86State *env = &cpu->env;
>> +
>> +    vmport_regs->ebx = env->regs[R_EBX];
>> +    vmport_regs->ecx = env->regs[R_ECX];
>> +    vmport_regs->edx = env->regs[R_EDX];
>> +    vmport_regs->esi = env->regs[R_ESI];
>> +    vmport_regs->edi = env->regs[R_EDI];
>> +}
>> +
>> +static void handle_vmport_ioreq(XenIOState *state, ioreq_t *req)
>> +{
>> +    vmware_regs_t *vmport_regs;
>> +
>> +    assert(state->shared_vmport_page);
>> +    vmport_regs =
>> +        &state->shared_vmport_page->vcpu_vmport_regs[state->send_vcpu];
>> +    BUILD_BUG_ON(sizeof(*req) < sizeof(*vmport_regs));
> QEMU_BUILD_BUG_ON
>
>
>> +    current_cpu = state->cpu_by_vcpu_id[state->send_vcpu];
>> +    regs_to_cpu(vmport_regs, req);
>> +    cpu_ioreq_pio(req);
>> +    regs_from_cpu(vmport_regs);
>> +    current_cpu = NULL;
>> +}
>> +
>> +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 +855,9 @@ 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 +899,7 @@ 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 +928,16 @@ 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 +977,14 @@ static void xen_main_loop_prepare(XenIOState *state)
>>                                                    state);
>>   
>>       if (evtchn_fd != -1) {
>> +        CPUState *cpu_state;
>> +
>> +        DPRINTF("%s: Init cpu_by_vcpu_id\n", __func__);
>> +        CPU_FOREACH(cpu_state) {
>> +            DPRINTF("%s: cpu_by_vcpu_id[%d]=%p\n",
>> +                    __func__, cpu_state->cpu_index, cpu_state);
>> +            state->cpu_by_vcpu_id[cpu_state->cpu_index] = cpu_state;
>> +        }
>>           qemu_set_fd_handler(evtchn_fd, cpu_handle_ioreq, NULL, state);
>>       }
>>   }
>> @@ -1020,6 +1101,20 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
>>                    errno, xen_xc);
>>       }
>>   
>> +    rc = xen_get_vmport_regs_pfn(xen_xc, xen_domid, &ioreq_pfn);
>> +    if (!rc) {
>> +        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);
>> +        }
>> +    } else if (rc != -ENOSYS) {
>> +        hw_error("get vmport regs pfn returned error %d, rc=%d", errno, rc);
>> +    }
>> +
>>       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 +1123,9 @@ 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_vcpu_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
>>