[Xen-devel] [RFC PATCH 3/3] remus: adjust x86 pv restore to support remus

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

cache vcpu context when restore, and set context when stream
complete.

Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
---
 tools/libxc/saverestore/common.h         |  6 +++
 tools/libxc/saverestore/restore_x86_pv.c | 67 ++++++++++++++++++++++----------
 2 files changed, 53 insertions(+), 20 deletions(-)

diff --git a/tools/libxc/saverestore/common.h b/tools/libxc/saverestore/common.h
index 1dd9f51..ba54f83 100644
--- a/tools/libxc/saverestore/common.h
+++ b/tools/libxc/saverestore/common.h
@@ -235,6 +235,12 @@ struct xc_sr_context
 
             /* Read-only mapping of guests shared info page */
             shared_info_any_t *shinfo;
+
+            /*
+             * We need to cache vcpu context when doing checkpointed
+             * restore, otherwise restore will fail
+             */
+            vcpu_guest_context_any_t *vcpu;
         } x86_pv;
     };
 };
diff --git a/tools/libxc/saverestore/restore_x86_pv.c 
b/tools/libxc/saverestore/restore_x86_pv.c
index 14fc020..7a54047 100644
--- a/tools/libxc/saverestore/restore_x86_pv.c
+++ b/tools/libxc/saverestore/restore_x86_pv.c
@@ -428,8 +428,8 @@ static int handle_x86_pv_vcpu_basic(struct xc_sr_context 
*ctx, struct xc_sr_reco
 {
     xc_interface *xch = ctx->xch;
     struct xc_sr_rec_x86_pv_vcpu_hdr *vhdr = rec->data;
-    vcpu_guest_context_any_t vcpu;
-    size_t vcpusz = ctx->x86_pv.width == 8 ? sizeof(vcpu.x64) : 
sizeof(vcpu.x32);
+    vcpu_guest_context_any_t *vcpu;
+    size_t vcpusz = ctx->x86_pv.width == 8 ? sizeof(vcpu->x64) : 
sizeof(vcpu->x32);
     xen_pfn_t pfn, mfn;
     unsigned long tmp;
     unsigned i;
@@ -455,22 +455,23 @@ static int handle_x86_pv_vcpu_basic(struct xc_sr_context 
*ctx, struct xc_sr_reco
         goto err;
     }
 
-    memcpy(&vcpu, &vhdr->context, vcpusz);
+    vcpu = (void *)ctx->x86_pv.vcpu + vcpusz * vhdr->vcpu_id;
+    memcpy(vcpu, &vhdr->context, vcpusz);
 
     /* Vcpu 0 is special: Convert the suspend record to an mfn. */
     if ( vhdr->vcpu_id == 0 )
     {
-        rc = process_start_info(ctx, &vcpu);
+        rc = process_start_info(ctx, vcpu);
         if ( rc )
             return rc;
         rc = -1;
     }
 
-    SET_FIELD(&vcpu, flags,
-              GET_FIELD(&vcpu, flags, ctx->x86_pv.width) | VGCF_online,
+    SET_FIELD(vcpu, flags,
+              GET_FIELD(vcpu, flags, ctx->x86_pv.width) | VGCF_online,
               ctx->x86_pv.width);
 
-    tmp = GET_FIELD(&vcpu, gdt_ents, ctx->x86_pv.width);
+    tmp = GET_FIELD(vcpu, gdt_ents, ctx->x86_pv.width);
     if ( tmp > 8192 )
     {
         ERROR("GDT entry count (%lu) out of range", tmp);
@@ -481,7 +482,7 @@ static int handle_x86_pv_vcpu_basic(struct xc_sr_context 
*ctx, struct xc_sr_reco
     /* Convert GDT frames to mfns. */
     for ( i = 0; (i * 512) < tmp; ++i )
     {
-        pfn = GET_FIELD(&vcpu, gdt_frames[i], ctx->x86_pv.width);
+        pfn = GET_FIELD(vcpu, gdt_frames[i], ctx->x86_pv.width);
         if ( pfn > ctx->x86_pv.max_pfn )
         {
             ERROR("GDT frame %u (pfn %#lx) out of range", i, pfn);
@@ -502,11 +503,11 @@ static int handle_x86_pv_vcpu_basic(struct xc_sr_context 
*ctx, struct xc_sr_reco
             goto err;
         }
 
-        SET_FIELD(&vcpu, gdt_frames[i], mfn, ctx->x86_pv.width);
+        SET_FIELD(vcpu, gdt_frames[i], mfn, ctx->x86_pv.width);
     }
 
     /* Convert CR3 to an mfn. */
-    pfn = cr3_to_mfn(ctx, GET_FIELD(&vcpu, ctrlreg[3], ctx->x86_pv.width));
+    pfn = cr3_to_mfn(ctx, GET_FIELD(vcpu, ctrlreg[3], ctx->x86_pv.width));
     if ( pfn > ctx->x86_pv.max_pfn )
     {
         ERROR("cr3 (pfn %#lx) out of range", pfn);
@@ -529,12 +530,12 @@ static int handle_x86_pv_vcpu_basic(struct xc_sr_context 
*ctx, struct xc_sr_reco
         goto err;
     }
 
-    SET_FIELD(&vcpu, ctrlreg[3], mfn_to_cr3(ctx, mfn), ctx->x86_pv.width);
+    SET_FIELD(vcpu, ctrlreg[3], mfn_to_cr3(ctx, mfn), ctx->x86_pv.width);
 
     /* 64bit guests: Convert CR1 (guest pagetables) to mfn. */
-    if ( ctx->x86_pv.levels == 4 && (vcpu.x64.ctrlreg[1] & 1) )
+    if ( ctx->x86_pv.levels == 4 && (vcpu->x64.ctrlreg[1] & 1) )
     {
-        pfn = vcpu.x64.ctrlreg[1] >> PAGE_SHIFT;
+        pfn = vcpu->x64.ctrlreg[1] >> PAGE_SHIFT;
 
         if ( pfn > ctx->x86_pv.max_pfn )
         {
@@ -558,13 +559,7 @@ static int handle_x86_pv_vcpu_basic(struct xc_sr_context 
*ctx, struct xc_sr_reco
             goto err;
         }
 
-        vcpu.x64.ctrlreg[1] = (uint64_t)mfn << PAGE_SHIFT;
-    }
-
-    if ( xc_vcpu_setcontext(xch, ctx->domid, vhdr->vcpu_id, &vcpu) )
-    {
-        PERROR("Failed to set vcpu%u's basic info", vhdr->vcpu_id);
-        goto err;
+        vcpu->x64.ctrlreg[1] = (uint64_t)mfn << PAGE_SHIFT;
     }
 
     rc = 0;
@@ -881,6 +876,7 @@ static int x86_pv_localise_page(struct xc_sr_context *ctx, 
uint32_t type, void *
 static int x86_pv_setup(struct xc_sr_context *ctx)
 {
     xc_interface *xch = ctx->xch;
+    size_t vcpusz;
     int rc;
 
     if ( ctx->restore.guest_type != DHDR_TYPE_X86_PV )
@@ -904,6 +900,9 @@ static int x86_pv_setup(struct xc_sr_context *ctx)
     if ( rc )
         return rc;
 
+    vcpusz = ctx->x86_pv.width == 8 ?
+             sizeof(ctx->x86_pv.vcpu->x64) : sizeof(ctx->x86_pv.vcpu->x32);
+    ctx->x86_pv.vcpu = calloc((ctx->dominfo.max_vcpu_id + 1) , vcpusz);
     return rc;
 }
 
@@ -946,6 +945,29 @@ static int x86_pv_process_record(struct xc_sr_context 
*ctx, struct xc_sr_record
     }
 }
 
+static int update_vcpu_context(struct xc_sr_context *ctx)
+{
+    xc_interface *xch = ctx->xch;
+    vcpu_guest_context_any_t *vcpu;
+    uint32_t vcpu_id;
+    size_t vcpusz = ctx->x86_pv.width == 8 ? sizeof(vcpu->x64) : 
sizeof(vcpu->x32);
+
+    for ( vcpu_id = 0; vcpu_id <= ctx->dominfo.max_vcpu_id; vcpu_id++ )
+    {
+        vcpu = (void *)ctx->x86_pv.vcpu + vcpu_id * vcpusz;
+        if ( !vcpu )
+            continue;
+
+        if ( xc_vcpu_setcontext(xch, ctx->domid, vcpu_id, vcpu) )
+        {
+            PERROR("Failed to set vcpu%u's basic info", vcpu_id);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
 /*
  * restore_ops function.  Pin the pagetables, rewrite the p2m and seed the
  * grant table.
@@ -963,6 +985,10 @@ static int x86_pv_stream_complete(struct xc_sr_context 
*ctx)
     if ( rc )
         return rc;
 
+    rc = update_vcpu_context(ctx);
+    if ( rc )
+        return rc;
+
     rc = xc_dom_gnttab_seed(xch, ctx->domid,
                             ctx->restore.console_mfn,
                             ctx->restore.xenstore_mfn,
@@ -985,6 +1011,7 @@ static int x86_pv_cleanup(struct xc_sr_context *ctx)
     free(ctx->x86_pv.p2m);
     free(ctx->x86_pv.p2m_pfns);
     free(ctx->x86_pv.pfn_types);
+    free(ctx->x86_pv.vcpu);
 
     if ( ctx->x86_pv.m2p )
         munmap(ctx->x86_pv.m2p, ctx->x86_pv.nr_m2p_frames * PAGE_SIZE);
-- 
1.9.1


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