Hi,

My board is Hikey on which have octa-core of arm cortex-a53. I have applied
patches [1] to try vm save/restore on arm.
These patches originally do not working on arm64. I have made some changes
based on patch set [2].

What I have got so far is

1. if I run 'xl save -p guest memState' to leave guest in suspend state,
then run 'xl unpause guest'.
    the guest can resume successfully. so I suppose the guest works find on
suspend/resume.

2. if I run 'xl restore -p memState' to restore guest and use xenctx to
dump all vcpu's registers.
    all the registers are identical to the state on save. After I run 'xl
unpause guest', I got no error but can not connect to console.
After restore the guest's PC is at a function
called user_disable_single_step(), which is called
by single_step_handler().

My question is

1. How could I debug guest on restore progress? are there any tools
available?
2. From my understanding, the restore not working is because some status is
missing when saving.
 e.g. on cpu_save, it know the domain is 64bit, but on cpu_load, it always
think it is a 32bit domain. so I have hard coded the domain type to
DOMAIN_64BIT.
Am I correct?
3. How could I dump all VM's status? I only found xenctx can dump vcpu's
registers.

I have attached my patch and log below.

Looking forward for your feedback.
Thanks

xl list
Name                                        ID   Mem VCPUs      State
Time(s)
Domain-0                                     0  1024     8     r-----
 11.7
root@linaro-alip:~# xl create guest.cfg
Parsing config from guest.cfg
[   39.238723] xen-blkback: ring-ref 8, event-channel 3, protocol 1
(arm-abi) persistent grants

root@linaro-alip:~# xl save -p guest memState
Saving to memState new xl format (info 0x3/0x0/931)
xc: info: Saving domain 1, type ARM
(XEN) HVM1 save: VCPU
(XEN) HVM1 save: A15_TIMER
(XEN) HVM1 save: GICV2_GICD
(XEN) HVM1 save: GICV2_GICC
(XEN) HVM1 save: GICV3
root@linaro-alip:~# /usr/lib/xen/bin/xenctx -a 1
PC:       ffffffc0000ab028
LR:       ffffffc00050458c
ELR_EL1:  ffffffc000086b34
CPSR:     200001c5
SPSR_EL1: 60000145
SP_EL0:   0000007ff6f2a850
SP_EL1:   ffffffc0140a7ca0

 x0: 0000000000000001    x1: 00000000deadbeef    x2: 0000000000000002
 x3: 0000000000000002    x4: 0000000000000004    x5: 0000000000000000
 x6: 000000000000001b    x7: 0000000000000001    x8: 000000618e589e00
 x9: 0000000000000000   x10: 0000000000000000   x11: 0000000000000000
x12: 00000000000001a3   x13: 000000001911a7d9   x14: 0000000000002ee0
x15: 0000000000000005   x16: 00000000deadbeef   x17: 0000000000000001
x18: 0000000000000007   x19: 0000000000000000   x20: ffffffc014163d58
x21: ffffffc014163cd8   x22: 0000000000000001   x23: 0000000000000140
x24: ffffffc000d5bb18   x25: ffffffc014163cd8   x26: 0000000000000000
x27: 0000000000000000   x28: 0000000000000000   x29: ffffffc0140a7ca0

SCTLR: 34d5d91d
TTBCR: 00000032b5193519
TTBR0: 002d000054876000
TTBR1: 0000000040dcf000
root@linaro-alip:~# xl destroy guest
(XEN) mm.c:1265:d0v1 gnttab_mark_dirty not implemented yet
root@linaro-alip:~# xl restore -p memState
Loading new save file memState (new xl fmt info 0x3/0x0/931)
 Savefile contains xl domain config in JSON format
Parsing config from <saved>
xc: info: (XEN) HVM2 restore: VCPU 0
Found ARM domain from Xen 4.7
xc: info: Restoring domain
(XEN) HVM2 restore: A15_TIMER 0
(XEN) HVM2 restore: A15_TIMER 0
(XEN) HVM2 restore: GICV2_GICD 0
(XEN) HVM2 restore: GICV2_GICC 0
(XEN) GICH_LRs (vcpu 0) mask=0
(XEN)    VCPU_LR[0]=0
(XEN)    VCPU_LR[1]=0
(XEN)    VCPU_LR[2]=0
(XEN)    VCPU_LR[3]=0
xc: info: Restore successful
xc: info: XenStore: mfn 0x39001, dom 0, evt 1
xc: info: Console: mfn 0x39000, dom 0, evt 2
root@linaro-alip:~# /usr/lib/xen/bin/xenctx -a 2
PC:       ffffffc0000ab028
LR:       ffffffc00050458c
ELR_EL1:  ffffffc000086b34
CPSR:     200001c5
SPSR_EL1: 60000145
SP_EL0:   0000007ff6f2a850
SP_EL1:   ffffffc0140a7ca0

 x0: 0000000000000000    x1: 00000000deadbeef    x2: 0000000000000002
 x3: 0000000000000002    x4: 0000000000000004    x5: 0000000000000000
 x6: 000000000000001b    x7: 0000000000000001    x8: 000000618e589e00
 x9: 0000000000000000   x10: 0000000000000000   x11: 0000000000000000
x12: 00000000000001a3   x13: 000000001911a7d9   x14: 0000000000002ee0
x15: 0000000000000005   x16: 00000000deadbeef   x17: 0000000000000001
x18: 0000000000000007   x19: 0000000000000000   x20: ffffffc014163d58
x21: ffffffc014163cd8   x22: 0000000000000001   x23: 0000000000000140
x24: ffffffc000d5bb18   x25: ffffffc014163cd8   x26: 0000000000000000
x27: 0000000000000000   x28: 0000000000000000   x29: ffffffc0140a7ca0

SCTLR: 34d5d91d
TTBCR: 00000000b5193519
TTBR0: 002d000054876000
TTBR1: 0000000040dcf000
root@linaro-alip:~# xl unpause guest
root@linaro-alip:~# xl list
Name                                        ID   Mem VCPUs      State
Time(s)
Domain-0                                     0  1024     8     r-----
 22.2
guest                                        2     0     1     r-----
4.8
root@linaro-alip:~# /usr/lib/xen/bin/xenctx -a 2
PC:       ffffffc000084a00
LR:       ffffffc00050458c
ELR_EL1:  ffffffc000084a00
CPSR:     000003c5
SPSR_EL1: 000003c5
SP_EL0:   0000007ff6f2a850
SP_EL1:   ffffffc0140a7ca0

 x0: 0000000000000000    x1: 00000000deadbeef    x2: 0000000000000002
 x3: 0000000000000002    x4: 0000000000000004    x5: 0000000000000000
 x6: 000000000000001b    x7: 0000000000000001    x8: 000000618e589e00
 x9: 0000000000000000   x10: 0000000000000000   x11: 0000000000000000
x12: 00000000000001a3   x13: 000000001911a7d9   x14: 0000000000002ee0
x15: 0000000000000005   x16: 00000000deadbeef   x17: 0000000000000001
x18: 0000000000000007   x19: 0000000000000000   x20: ffffffc014163d58
x21: ffffffc014163cd8   x22: 0000000000000001   x23: 0000000000000140
x24: ffffffc000d5bb18   x25: ffffffc014163cd8   x26: 0000000000000000
x27: 0000000000000000   x28: 0000000000000000   x29: ffffffc0140a7ca0

SCTLR: 34d5d91d
TTBCR: 00000000b5193519
TTBR0: 002d000054876000
TTBR1: 0000000040dcf000
root@linaro-alip:~# xl console guest
xenconsole: Could not read tty from store: Success
root@linaro-alip:~#


diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
index aee3353..411bab4 100644
--- a/xen/arch/arm/hvm.c
+++ b/xen/arch/arm/hvm.c
@@ -120,7 +120,8 @@ static int cpu_save(struct domain *d,
hvm_domain_context_t *h)
         ctxt.dfar = v->arch.dfar;
         ctxt.dfsr = v->arch.dfsr;
 #else
-        /* XXX 64-bit */
+       ctxt.far = v->arch.far;
+       ctxt.esr = v->arch.esr;
 #endif

 #ifdef CONFIG_ARM_32
@@ -187,6 +188,9 @@ static int cpu_load(struct domain *d,
hvm_domain_context_t *h)
     if ( hvm_load_entry(VCPU, h, &ctxt) != 0 )
         return -EINVAL;

+#ifdef CONFIG_ARM64
+    v->arch.type = DOMAIN_64BIT;
+#endif
     v->arch.sctlr = ctxt.sctlr;
     v->arch.ttbr0 = ctxt.ttbr0;
     v->arch.ttbr1 = ctxt.ttbr1;
@@ -199,7 +203,8 @@ static int cpu_load(struct domain *d,
hvm_domain_context_t *h)
     v->arch.dfar = ctxt.dfar;
     v->arch.dfsr = ctxt.dfsr;
 #else
-    /* XXX 64-bit */
+    v->arch.far = ctxt.far;
+    v->arch.esr = ctxt.esr;
 #endif

 #ifdef CONFIG_ARM_32
diff --git a/xen/include/public/arch-arm/hvm/save.h
b/xen/include/public/arch-arm/hvm/save.h
index db916b1..89e6e89 100644
--- a/xen/include/public/arch-arm/hvm/save.h
+++ b/xen/include/public/arch-arm/hvm/save.h
@@ -46,8 +46,12 @@ DECLARE_HVM_SAVE_TYPE(HEADER, 1, struct hvm_save_header);

 struct hvm_hw_cpu
 {
+#ifdef CONFIG_ARM_32
     uint64_t vfp[34]; /* Vector floating pointer */
     /* VFP v3 state is 34x64 bit, VFP v4 is not yet supported */
+#else
+    uint64_t vfp[66];
+#endif

     /* Guest core registers */
     struct vcpu_guest_core_regs core_regs;
@@ -60,6 +64,9 @@ struct hvm_hw_cpu
     uint32_t dacr;
     uint64_t par;

+    uint64_t far;
+    uint64_t esr;
+
     uint64_t mair0, mair1;
     uint64_t tpidr_el0;
     uint64_t tpidr_el1;



[1] http://lists.xen.org/archives/html/xen-devel/2015-12/msg01053.html
[2] http://lists.xen.org/archives/html/xen-devel/2014-04/msg01544.html