x86, kvm: common confidential computing subset

[PATCH 21/26] kvm/memory: Make memory type private by default if it has guest memfd backend

Paolo Bonzini posted 26 patches 1 year, 10 months ago

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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, David Hildenbrand <david@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, "Michael S. Tsirkin" <mst@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Peter Xu <peterx@redhat.com>, Cornelia Huck <cohuck@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Marcelo Tosatti <mtosatti@redhat.com>, Song Gao <gaosong@loongson.cn>, Huacai Chen <chenhuacai@kernel.org>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Bin Meng <bin.meng@windriver.com>, Weiwei Li <liwei1518@gmail.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>

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[PATCH 21/26] kvm/memory: Make memory type private by default if it has guest memfd backend

Posted by Paolo Bonzini 1 year, 10 months ago

From: Xiaoyao Li <xiaoyao.li@intel.com>

KVM side leaves the memory to shared by default, while may incur the
overhead of paging conversion on the first visit of each page. Because
the expectation is that page is likely to private for the VMs that
require private memory (has guest memfd).

Explicitly set the memory to private when memory region has valid
guest memfd backend.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Message-ID: <20240320083945.991426-16-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/kvm/kvm-all.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 7fbaf31cbaf..56b17cbd8aa 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1430,6 +1430,16 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
                     strerror(-err));
             abort();
         }
+
+        if (memory_region_has_guest_memfd(mr)) {
+            err = kvm_set_memory_attributes_private(start_addr, slot_size);
+            if (err) {
+                error_report("%s: failed to set memory attribute private: %s\n",
+                             __func__, strerror(-err));
+                exit(1);
+            }
+        }
+
         start_addr += slot_size;
         ram_start_offset += slot_size;
         ram += slot_size;
-- 
2.44.0

Re: [PATCH 21/26] kvm/memory: Make memory type private by default if it has guest memfd backend

Posted by Xiaoyao Li 1 year, 10 months ago

On 3/23/2024 2:11 AM, Paolo Bonzini wrote:
> From: Xiaoyao Li <xiaoyao.li@intel.com>
> 
> KVM side leaves the memory to shared by default, while may incur the

/s/while/which/

fix typo from myself.

> overhead of paging conversion on the first visit of each page. Because
> the expectation is that page is likely to private for the VMs that
> require private memory (has guest memfd).
> 
> Explicitly set the memory to private when memory region has valid
> guest memfd backend.
> 
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Michael Roth <michael.roth@amd.com>
> Message-ID: <20240320083945.991426-16-michael.roth@amd.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   accel/kvm/kvm-all.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 7fbaf31cbaf..56b17cbd8aa 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -1430,6 +1430,16 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
>                       strerror(-err));
>               abort();
>           }
> +
> +        if (memory_region_has_guest_memfd(mr)) {
> +            err = kvm_set_memory_attributes_private(start_addr, slot_size);
> +            if (err) {
> +                error_report("%s: failed to set memory attribute private: %s\n",
> +                             __func__, strerror(-err));
> +                exit(1);
> +            }
> +        }
> +
>           start_addr += slot_size;
>           ram_start_offset += slot_size;
>           ram += slot_size;