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From: Chenyi Qiang <chenyi.qiang@intel.com>
To: "Peter Xu" <peterx@redhat.com>,
	"David Hildenbrand" <david@redhat.com>,
	"Alexey Kardashevskiy" <aik@amd.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>
Cc: Chenyi Qiang <chenyi.qiang@intel.com>,
	qemu-devel@nongnu.org, Gao Chao <chao.gao@intel.com>,
	Li Xiaoyao <xiaoyao.li@intel.com>
Subject: [PATCH] ram-block-attributes: Avoid the overkill of shared memory with hugetlbfs backend
Date: Fri, 17 Oct 2025 16:14:23 +0800	[thread overview]
Message-ID: <20251017081445.175342-1-chenyi.qiang@intel.com> (raw)

Currently, private memory and shared memory have different backend in
CoCo VMs. It is possible for users to specify the shared memory with
hugetlbfs backend while private memory with guest_memfd backend only
supports 4K page size. In this case, ram_block->page_size is different
from the host page size which will trigger the assertion when getting
block size. Relax the restriction to allow shared memory to use
hugetlbfs backend.

Fixes: 5d6483edaa92 ("ram-block-attributes: Introduce RamBlockAttributes to manage RAMBlock with guest_memfd")
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
---
 system/ram-block-attributes.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/system/ram-block-attributes.c b/system/ram-block-attributes.c
index 68e8a027032..0f39ccf9090 100644
--- a/system/ram-block-attributes.c
+++ b/system/ram-block-attributes.c
@@ -28,10 +28,11 @@ ram_block_attributes_get_block_size(const RamBlockAttributes *attr)
      * Because page conversion could be manipulated in the size of at least 4K
      * or 4K aligned, Use the host page size as the granularity to track the
      * memory attribute.
+     * When hugetlbfs is used as backend of shared memory, ram_block->page_size
+     * is different from host page size. So it is not appropriate to use
+     * ram_block->page_size here.
      */
-    g_assert(attr && attr->ram_block);
-    g_assert(attr->ram_block->page_size == qemu_real_host_page_size());
-    return attr->ram_block->page_size;
+    return qemu_real_host_page_size();
 }
 
 
-- 
2.43.5



             reply	other threads:[~2025-10-17  8:15 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-17  8:14 Chenyi Qiang [this message]
2025-10-17 13:57 ` [PATCH] ram-block-attributes: Avoid the overkill of shared memory with hugetlbfs backend Peter Xu
2025-10-17 15:13 ` David Hildenbrand
2025-10-20 10:32   ` Chenyi Qiang
2025-10-20 11:31     ` David Hildenbrand
2025-10-20 11:48       ` Chenyi Qiang
2025-10-20 11:34 ` David Hildenbrand

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