CI: Switch to r8g.xlarge for CBMC proofs

This PR ports pq-code-package/mlkem-native#1250

The r instances have a higher Memory/vCPU ratio and are therefore
more suited for the memory-hungry CBMC tests. Specifically, r8g.xlarge
has the same RAM as c7g.4xlarge, a newer generation Graviton core,
and at the time of writing currently comes at a lower price point.

Therefore, this commit modifies the CBMC CI job to use r8g.xlarge
instances instead of c7g.4xlarge.

Signed-off-by: Matthias J. Kannwischer <[email protected]>

Author: mkannwischer

.github/workflows/cbmc.yml

@@ -17,9 +17,9 @@ jobs:
     uses: ./.github/workflows/ci_ec2_reusable.yml
     with:
       name: CBMC (ML-DSA-44)
-      ec2_instance_type: c7g.4xlarge
-      ec2_ami: ubuntu-latest (custom AMI)
-      ec2_ami_id: ami-0d7f502261b31b27f # aarch64, ubuntu-latest, 64g
+      ec2_instance_type: r8g.xlarge
+      ec2_ami: ubuntu-latest (aarch64)
+      ec2_volume_size: 20
       compile_mode: native
       opt: no_opt
       lint: false
@@ -39,9 +39,9 @@ jobs:
     uses: ./.github/workflows/ci_ec2_reusable.yml
     with:
       name: CBMC (ML-DSA-65)
-      ec2_instance_type: c7g.4xlarge
-      ec2_ami: ubuntu-latest (custom AMI)
-      ec2_ami_id: ami-0d7f502261b31b27f # aarch64, ubuntu-latest, 64g
+      ec2_instance_type: r8g.xlarge
+      ec2_ami: ubuntu-latest (aarch64)
+      ec2_volume_size: 20
       compile_mode: native
       opt: no_opt
       lint: false
@@ -61,9 +61,9 @@ jobs:
     uses: ./.github/workflows/ci_ec2_reusable.yml
     with:
       name: CBMC (ML-DSA-87)
-      ec2_instance_type: c7g.4xlarge
-      ec2_ami: ubuntu-latest (custom AMI)
-      ec2_ami_id: ami-0d7f502261b31b27f # aarch64, ubuntu-latest, 64g
+      ec2_instance_type: r8g.xlarge
+      ec2_ami: ubuntu-latest (aarch64)
+      ec2_volume_size: 20
       compile_mode: native
       opt: no_opt
       lint: false

.github/workflows/ci_ec2_reusable.yml

@@ -24,6 +24,9 @@ on:
         type: string
         description: AMI ID
         default: ami-0e8c824f386e1de06
+      ec2_volume_size:
+        type: string
+        default: ""
       cflags:
         type: string
         description: Custom CFLAGS for compilation
@@ -113,6 +116,7 @@ jobs:
           mode: start
           github-token: ${{ secrets.AWS_GITHUB_TOKEN }}
           ec2-image-id: ${{ steps.det_ami_id.outputs.AMI_ID }}
+          ec2-volume-size: ${{ inputs.ec2_volume_size }}
           ec2-instance-type: ${{ inputs.ec2_instance_type }}
           subnet-id: subnet-094d73eb42eb6bf5b
           security-group-id: sg-0282706dbc92a1579
@@ -130,6 +134,7 @@ jobs:
           mode: start
           github-token: ${{ secrets.AWS_GITHUB_TOKEN }}
           ec2-image-id: ${{ steps.det_ami_id.outputs.AMI_ID }}
+          ec2-volume-size: ${{ inputs.ec2_volume_size }}
           ec2-instance-type: ${{ inputs.ec2_instance_type }}
           subnet-id: subnet-094d73eb42eb6bf5b
           security-group-id: sg-0282706dbc92a1579