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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v16 01/10] x86: add generic resource (e.g. MSR) access hypercall
On 25/09/14 11:19, Chao Peng wrote:
> Add a generic resource access hypercall for tool stack or other
> components, e.g., accessing MSR, port I/O, etc.
>
> Signed-off-by: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
> Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> ---
> xen/arch/x86/platform_hypercall.c | 90
> ++++++++++++++++++++++++++++++
> xen/arch/x86/x86_64/platform_hypercall.c | 4 ++
> xen/include/public/platform.h | 23 ++++++++
> xen/include/xlat.lst | 2 +
> 4 files changed, 119 insertions(+)
>
> diff --git a/xen/arch/x86/platform_hypercall.c
> b/xen/arch/x86/platform_hypercall.c
> index 2162811..081d9f5 100644
> --- a/xen/arch/x86/platform_hypercall.c
> +++ b/xen/arch/x86/platform_hypercall.c
> @@ -61,6 +61,68 @@ long cpu_down_helper(void *data);
> long core_parking_helper(void *data);
> uint32_t get_cur_idle_nums(void);
>
> +struct xen_resource_access {
> + int32_t ret;
> + uint32_t nr;
> + XEN_GUEST_HANDLE(xenpf_resource_data_t) data;
> +};
> +
> +static bool_t allow_access_msr(unsigned int msr)
> +{
> + return 0;
> +}
> +
> +static void resource_access(void *info)
> +{
> + struct xen_resource_access *ra = info;
> + xenpf_resource_data_t data;
> + int ret = 0;
> + unsigned int i;
> +
> + for ( i = 0; i < ra->nr; i++ )
> + {
> + if ( copy_from_guest_offset(&data, ra->data, i, 1) )
You cannot use copy_{to,from}_guest() here. You are almost certainly on
the wrong cpu, and running on the wrong set of pagetables.
At best, you will copy bogus data from the wrong process/domain, and
likely corrupt it when copying back.
> + {
> + ret = -EFAULT;
> + break;
> + }
> +
> + if ( data.rsvd ) {
> + ret = -EINVAL;
> + break;
> + }
> +
> + switch ( data.cmd )
> + {
> + case XEN_RESOURCE_OP_MSR_READ:
> + case XEN_RESOURCE_OP_MSR_WRITE:
> + if ( data.idx >> 32 )
> + ret = -EINVAL;
> + else if ( !allow_access_msr(data.idx) )
> + ret = -EACCES;
> + else if ( data.cmd == XEN_RESOURCE_OP_MSR_READ )
> + ret = rdmsr_safe(data.idx, data.val);
> + else
> + ret = wrmsr_safe(data.idx, data.val);
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> +
> + if ( ret )
> + break;
> +
> + if ( copy_to_guest_offset(ra->data, i, &data, 1) )
> + {
> + ret = -EFAULT;
> + break;
> + }
> + }
> +
> + ra->ret = ret;
> +}
> +
> ret_t do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
> {
> ret_t ret = 0;
> @@ -601,6 +663,34 @@ ret_t
> do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
> }
> break;
>
> + case XENPF_resource_op:
> + {
> + struct xen_resource_access ra;
> + struct xenpf_resource_op *rsc_op = &op->u.resource_op;
> + unsigned int cpu = smp_processor_id();
> +
> + ra.nr = rsc_op->nr;
> + ra.data = rsc_op->data;
You must do all copy_{from,to}_user() here, and strictly only pass Xen
pointers to resource_access().
This means you will need to xmalloc() yourself some space for the
xenpf_resource_data_t array.
On a different note, you need to enforce a maximum resource_op.nr of
something rather low to (16/32 perhaps?) to prevent a toolstack asking
for 0xffffffff non-preemptible operations.
~Andrew
> +
> + if ( rsc_op->cpu == cpu )
> + resource_access(&ra);
> + else if ( cpu_online(rsc_op->cpu) )
> + on_selected_cpus(cpumask_of(rsc_op->cpu),
> + resource_access, &ra, 1);
> + else
> + {
> + ret = -ENODEV;
> + break;
> + }
> +
> + if ( ra.ret )
> + {
> + ret = ra.ret;
> + break;
> + }
> + }
> + break;
> +
> default:
> ret = -ENOSYS;
> break;
> diff --git a/xen/arch/x86/x86_64/platform_hypercall.c
> b/xen/arch/x86/x86_64/platform_hypercall.c
> index b6f380e..4db6622 100644
> --- a/xen/arch/x86/x86_64/platform_hypercall.c
> +++ b/xen/arch/x86/x86_64/platform_hypercall.c
> @@ -32,6 +32,10 @@ CHECK_pf_pcpu_version;
> CHECK_pf_enter_acpi_sleep;
> #undef xen_pf_enter_acpi_sleep
>
> +#define xen_pf_resource_data xenpf_resource_data
> +CHECK_pf_resource_data;
> +#undef xen_pf_resource_data
> +
> #define COMPAT
> #define _XEN_GUEST_HANDLE(t) XEN_GUEST_HANDLE(t)
> #define _XEN_GUEST_HANDLE_PARAM(t) XEN_GUEST_HANDLE_PARAM(t)
> diff --git a/xen/include/public/platform.h b/xen/include/public/platform.h
> index 053b9fa..e4d9091 100644
> --- a/xen/include/public/platform.h
> +++ b/xen/include/public/platform.h
> @@ -527,6 +527,28 @@ struct xenpf_core_parking {
> typedef struct xenpf_core_parking xenpf_core_parking_t;
> DEFINE_XEN_GUEST_HANDLE(xenpf_core_parking_t);
>
> +#define XENPF_resource_op 61
> +
> +#define XEN_RESOURCE_OP_MSR_READ 0
> +#define XEN_RESOURCE_OP_MSR_WRITE 1
> +
> +struct xenpf_resource_data {
> + uint32_t cmd; /* XEN_RESOURCE_OP_* */
> + uint32_t rsvd;
> + uint64_t idx;
> + uint64_t val;
> +};
> +typedef struct xenpf_resource_data xenpf_resource_data_t;
> +DEFINE_XEN_GUEST_HANDLE(xenpf_resource_data_t);
> +
> +struct xenpf_resource_op {
> + uint32_t nr; /* number of data entry */
> + uint32_t cpu; /* which cpu to run */
> + XEN_GUEST_HANDLE(xenpf_resource_data_t) data;
> +};
> +typedef struct xenpf_resource_op xenpf_resource_op_t;
> +DEFINE_XEN_GUEST_HANDLE(xenpf_resource_op_t);
> +
> /*
> * ` enum neg_errnoval
> * ` HYPERVISOR_platform_op(const struct xen_platform_op*);
> @@ -553,6 +575,7 @@ struct xen_platform_op {
> struct xenpf_cpu_hotadd cpu_add;
> struct xenpf_mem_hotadd mem_add;
> struct xenpf_core_parking core_parking;
> + struct xenpf_resource_op resource_op;
> uint8_t pad[128];
> } u;
> };
> diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
> index 9a35dd7..100fcf5 100644
> --- a/xen/include/xlat.lst
> +++ b/xen/include/xlat.lst
> @@ -88,6 +88,8 @@
> ? xenpf_enter_acpi_sleep platform.h
> ? xenpf_pcpuinfo platform.h
> ? xenpf_pcpu_version platform.h
> +? xenpf_resource_op platform.h
> +? xenpf_resource_data platform.h
> ! sched_poll sched.h
> ? sched_remote_shutdown sched.h
> ? sched_shutdown sched.h
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