[6.6-velinux] Intel: backport KVM Fix for Clearing SGX EDECCSSA to 6.6

[zhiquan1-li]

Description
When SGX EDECCSSA support was added to KVM in commit 16a7fe3 ("KVM/VMX: Allow exposing EDECCSSA user leaf function to KVM guest"), it forgot to clear the X86_FEATURE_SGX_EDECCSSA bit in KVM CPU caps when KVM SGX is disabled. Fix it.

Fixes: 16a7fe3 ("KVM/VMX: Allow exposing EDECCSSA user leaf function to KVM guest")

About the patches
The total patch number is 1:

7efb4d8a392a KVM: VMX: Also clear SGX EDECCSSA in KVM CPU caps when SGX is disabled

Tests

1. Build successfully for each commit
2. Kernel selftest - SGX: PASSED

cd tools/testing/selftests/sgx/
make
./test_sgx

3. Kernel selftest - SGX in VM: PASSED
4. Function test

Step 1. Original SGX EDECCSSA status in guest

[root@guest ~]# cpuid -1 -l 0x12
CPU:
   Software Guard Extensions (SGX) capability (0x12/0):
      SGX1 supported                           = true
      SGX2 supported                           = true
      SGX ENCLV E*VIRTCHILD, ESETCONTEXT       = false
      SGX ENCLS ETRACKC, ERDINFO, ELDBC, ELDUC = false
      SGX ENCLU EVERIFYREPORT2                 = false
      SGX ENCLS EUPDATESVN                     = false
      SGX ENCLU EDECCSSA                       = true
      MISCSELECT.EXINFO supported: #PF & #GP   = true
      MISCSELECT.CPINFO supported: #CP         = false
      MaxEnclaveSize_Not64 (log2)              = 0x1f (31)
      MaxEnclaveSize_64 (log2)                 = 0x38 (56)

Step 2. Disable SGX in guest

root@KVM-host:~# rmmod kvm_intel
root@KVM-host:~# modprobe kvm_intel sgx=0 

Step 3. The SGX EDECCSSA capability is cleared in KVM, then its status becomes false

[root@guest ~]# cpuid -1 -l 0x12
CPU:
   Software Guard Extensions (SGX) capability (0x12/0):
      SGX1 supported                           = false
      SGX2 supported                           = false
      SGX ENCLV E*VIRTCHILD, ESETCONTEXT       = false
      SGX ENCLS ETRACKC, ERDINFO, ELDBC, ELDUC = false
      SGX ENCLU EVERIFYREPORT2                 = false
      SGX ENCLS EUPDATESVN                     = false
      SGX ENCLU EDECCSSA                       = false
      MISCSELECT.EXINFO supported: #PF & #GP   = false
      MISCSELECT.CPINFO supported: #CP         = false
      MaxEnclaveSize_Not64 (log2)              = 0x0 (0)
      MaxEnclaveSize_64 (log2)                 = 0x0 (0)
[root@TDX-guest ~]# 

Known issue:
None

Default config change:
None