On 9/22/2023 3:08 PM, David Hildenbrand wrote:
On 22.09.23 02:22, Xiaoyao Li wrote:
On 9/21/2023 4:55 PM, David Hildenbrand wrote:
On 14.09.23 05:50, Xiaoyao Li wrote:
From: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
Add KVM gmem support to RAMBlock so both normal hva based memory
and kvm gmem fd based private memory can be associated in one RAMBlock.
Introduce new flag RAM_KVM_GMEM. It calls KVM ioctl to create private
gmem for the RAMBlock when it's set.
But who sets RAM_KVM_GMEM and when?
The answer is in the next patch. When `private` property of memory
backend is set to true, it will pass RAM_KVM_GMEM flag to
memory_region_init_ram_*()
Okay, assuming that patch (and property) will go away, I assume this
flag can also go away, right?
If dropping the flag RAM_KVM_GMEM, it seems we need go back to the
approach of rfc v1[1][2], that allocating gmem inside .region_add()
callback. Is it accepted by you?
Another option is allocating gmem inside ram_block_add() by checking the
vm_type (it looks hacky for me). What's your opinion on this option?
One more option is, we keep the RAM_KVM_GMEM as this patch, and change
"private" property of memory backend into "need_kvm_gmem" field (make it
not user settable) and "need_kvm_gmem" field will be set to true in
tdx_kvm_init() specific cgs initialization function.
[1]
https://lore.kernel.org/qemu-devel/a154c33d-b24d-b713-0dc0-027d54f2340f@xxxxxxxxxx/
[2]
https://lore.kernel.org/qemu-devel/20230731162201.271114-10-xiaoyao.li@xxxxxxxxx/
