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

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;

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).


Anthony Liguori

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