[Xen-devel] Re: [PATCH 4/8] HVM save restore: vcpu context support

[Anthony Liguori <aliguori@xxxxxxxxxxxxxxxxxx>]

Zhai, Edwin wrote:
> [PATCH 4/8] HVM save restore: vcpu context support
>
> Signed-off-by: Zhai Edwin <edwin.zhai@xxxxxxxxx>
>
>  typedef uint64_t tsc_timestamp_t; /* RDTSC timestamp */
> +
> +/*
> + * World vmcs state
> + */
> +struct vmcs_data {
> +    uint64_t  eip;        /* execution pointer */
> +    uint64_t  esp;        /* stack pointer */
> +    uint64_t  eflags;     /* flags register */
> +    uint64_t  cr0;
> +    uint64_t  cr3;        /* page table directory */
> +    uint64_t  cr4;
> +    uint32_t  idtr_limit; /* idt */
> +    uint64_t  idtr_base;
If I read the code correctly, vmcs_data ends up becoming part of:

+
+#define HVM_CTXT_SIZE        6144
+typedef struct hvm_domain_context {
+    uint32_t cur;
+    uint32_t size;
+    uint8_t data[HVM_CTXT_SIZE];
+} hvm_domain_context_t;
+DEFINE_XEN_GUEST_HANDLE(hvm_domain_context_t);

Which then gets saved to disk.  My first concern would be that struct 
vmcs_data is not padding safe.  How idtr_limit gets padding may change 
in future versions of GCC which would break the save format.
The second is how HVM_CTXT_SIZE gets defined.  Not sure there's a great 
way to address though (although the first issue is definitely fixable).
Regards,

Anthony Liguori

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel