Introduce support for confidential guest reset

[PATCH v1 03/28] system/physmem: add helper to reattach existing memory after KVM VM fd change

Ani Sinha posted 28 patches 1 day, 15 hours ago

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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, David Woodhouse <dwmw2@infradead.org>, Paul Durrant <paul@xen.org>, Bernhard Beschow <shentey@gmail.com>, Alex Williamson <alex@shazbot.org>, "Cédric Le Goater" <clg@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Peter Xu <peterx@redhat.com>, David Hildenbrand <david@kernel.org>, Peter Maydell <peter.maydell@linaro.org>, Marcelo Tosatti <mtosatti@redhat.com>, Zhao Liu <zhao1.liu@intel.com>, Song Gao <gaosong@loongson.cn>, Huacai Chen <chenhuacai@kernel.org>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <arikalo@gmail.com>, Nicholas Piggin <npiggin@gmail.com>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Chinmay Rath <rathc@linux.ibm.com>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Weiwei Li <liwei1518@gmail.com>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Matthew Rosato <mjrosato@linux.ibm.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>

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[PATCH v1 03/28] system/physmem: add helper to reattach existing memory after KVM VM fd change

Posted by Ani Sinha 1 day, 15 hours ago

After the guest KVM file descriptor has changed as a part of the process of
confidential guest reset mechanism, existing memory needs to be reattached to
the new file descriptor. This change adds a helper function ram_block_rebind()
for this purpose. The next patch will make use of this function.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 include/system/physmem.h |  1 +
 system/physmem.c         | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/include/system/physmem.h b/include/system/physmem.h
index 879f6eae38..bfc0a623ac 100644
--- a/include/system/physmem.h
+++ b/include/system/physmem.h
@@ -50,5 +50,6 @@ physical_memory_snapshot_and_clear_dirty(MemoryRegion *mr, hwaddr offset,
 bool physical_memory_snapshot_get_dirty(DirtyBitmapSnapshot *snap,
                                         ram_addr_t start,
                                         ram_addr_t length);
+int ram_block_rebind(Error **errp);
 
 #endif
diff --git a/system/physmem.c b/system/physmem.c
index c9869e4049..9a3e3c16f8 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -2839,6 +2839,34 @@ found:
     return block;
 }
 
+/*
+ * Creates new guest memfd for the ramblocks and closes the
+ * existing memfd.
+ */
+int ram_block_rebind(Error **errp)
+{
+    RAMBlock *block;
+
+    qemu_mutex_lock_ramlist();
+
+    RAMBLOCK_FOREACH(block) {
+        if (block->flags & RAM_GUEST_MEMFD) {
+            if (block->guest_memfd >= 0) {
+                close(block->guest_memfd);
+            }
+            block->guest_memfd = kvm_create_guest_memfd(block->max_length,
+                                                        0, errp);
+            if (block->guest_memfd < 0) {
+                qemu_mutex_unlock_ramlist();
+                return -1;
+            }
+
+        }
+    }
+    qemu_mutex_unlock_ramlist();
+    return 0;
+}
+
 /*
  * Finds the named RAMBlock
  *
-- 
2.42.0