test: test_host_vs_guest_cpu_features on Intel Sapphire Rapids

Intel Sapphire Rapids has some new features compared to older Intel
processors. Some of them are just not virtualized by KVM, others started
to be passed through to guests since specific kernel versions, and the
others can be emulated but now supported by hardware.

Signed-off-by: Takahiro Itazuri <[email protected]>

Author: zulinx86

tests/integration_tests/functional/test_cpu_features_host_vs_guest.py

@@ -233,6 +233,102 @@ def test_host_vs_guest_cpu_features(uvm_plain_any):
                 assert host_feats - guest_feats == host_guest_diff_6_1
             assert guest_feats - host_feats == INTEL_GUEST_ONLY_FEATS - {"umip"}
 
+        case CpuModel.INTEL_SAPPHIRE_RAPIDS:
+            expected_host_minus_guest = INTEL_HOST_ONLY_FEATS.copy()
+            expected_guest_minus_host = INTEL_GUEST_ONLY_FEATS.copy()
+
+            host_version = global_props.host_linux_version_tpl
+            guest_version = vm.guest_kernel_version
+
+            # KVM does not support virtualization of the following hardware features yet for several
+            # reasons (e.g. security, simply difficulty of implementation).
+            expected_host_minus_guest |= {
+                # Intel Total Memory Encryption (TME) is the capability to encrypt the entirety of
+                # physical memory of a system. TME is enabled by system BIOS/hardware and applies to
+                # the phyiscal memory as a whole.
+                "tme",
+                # PCONFIG instruction allows software to configure certain platform features. It
+                # supports these features multiple leaf functions, selecting a leaf function using
+                # the value in EAX. As of this writing, the only defined PCONFIG leaf function is
+                # for key programming for total memory encryption-multi-key (TME-MK).
+                "pconfig",
+                # Architectural Last Branch Record (Arch LBR) that is a feature that logs the most
+                # recently executed branch instructions (e.g. source and destination addresses).
+                # Tradiaional LBR implementations have existed in Intel CPUs for years and the MSR
+                # interface varied by CPU model. Arch LBR is a standardized version. There is a
+                # kernel patch created in 2022 but didn't get merged due to a mess.
+                # https://lore.kernel.org/all/[email protected]/
+                "arch_lbr",
+                # ENQCMD/ENQCMDS are instructions that allow software to atomically write 64-byte
+                # commands to enqueue registers, which are special device registers accessed using
+                # memory-mapped I/O.
+                "enqcmd",
+                # Intel Resource Director Technology (RDT) feature set provides a set of allocation
+                # (resource control) capabilities including Cache Allocation Technology (CAT) and
+                # Code and Data Prioritization (CDP).
+                # L3 variants are listed in INTEL_HOST_ONLY_FEATS.
+                "cat_l2",
+                "cdp_l2",
+                # This is a synthesized bit for split lock detection that raise an Alignment Check
+                # (#AC) exception if an operand of an atomic operation crosses two cache lines. It
+                # is not enumerated on CPUID, instead detected by actually attempting to read from
+                # MSR address 0x33 (MSR_MEMORY_CTRL in Intel SDM, MSR_TEST_CTRL in Linux kernel).
+                "split_lock_detect",
+            }
+
+            # The following features are also not virtualized by KVM yet but are only supported on
+            # newer kernel versions.
+            if host_version >= (5, 18):
+                expected_host_minus_guest |= {
+                    # Hardware Feedback Interface (HFI) is a feature that gives OSes a performance
+                    # and energy efficiency capability data for each CPU that can be used to
+                    # influence task placement decisions.
+                    # https://github.com/torvalds/linux/commit/7b8f40b3de75c971a4e5f9308b06deb59118dbac
+                    "hfi",
+                    # Indirect Brach Tracking (IBT) is a feature where the CPU ensures that indirect
+                    # branch targets start with ENDBRANCH instruction (`endbr32` or `endbr64`),
+                    # which executes as a no-op; if anything else is found, a control-protection
+                    # (#CP) fault will be raised.
+                    # https://github.com/torvalds/linux/commit/991625f3dd2cbc4b787deb0213e2bcf8fa264b21
+                    "ibt",
+                }
+
+            # AVX512 FP16 is supported and passed through on v5.11+.
+            # https://github.com/torvalds/linux/commit/e1b35da5e624f8b09d2e98845c2e4c84b179d9a4
+            # https://github.com/torvalds/linux/commit/2224fc9efb2d6593fbfb57287e39ba4958b188ba
+            if host_version >= (5, 11) and guest_version < (5, 11):
+                expected_host_minus_guest |= {"avx512_fp16"}
+
+            # AVX VNNI support is supported and passed through on v5.12+.
+            # https://github.com/torvalds/linux/commit/b85a0425d8056f3bd8d0a94ecdddf2a39d32a801
+            # https://github.com/torvalds/linux/commit/1085a6b585d7d1c441cd10fdb4c7a4d96a22eba7
+            if host_version >= (5, 12) and guest_version < (5, 12):
+                expected_host_minus_guest |= {"avx_vnni"}
+
+            # Bus lock detection is supported on v5.12+ and passed through on v5.13+.
+            # https://github.com/torvalds/linux/commit/f21d4d3b97a8603567e5d4250bd75e8ebbd520af
+            # https://github.com/torvalds/linux/commit/76ea438b4afcd9ee8da3387e9af4625eaccff58f
+            if host_version >= (5, 13) and guest_version < (5, 12):
+                expected_host_minus_guest |= {"bus_lock_detect"}
+
+            # Intel AMX is supported and passed through on v5.17+.
+            # https://github.com/torvalds/linux/commit/690a757d610e50c2c3acd2e4bc3992cfc63feff2
+            if host_version >= (5, 17) and guest_version < (5, 17):
+                expected_host_minus_guest |= {"amx_bf16", "amx_int8", "amx_tile"}
+
+            expected_guest_minus_host -= {
+                # UMIP can be emulated by KVM on Intel processors, but is supported in hardware on
+                # Intel Sapphire Rapids and passed through.
+                "umip",
+                # This is a synthesized bit and it is always set on guest thanks to kvm-clock. But
+                # Intel Sapphire Rapids reports TSC frequency on CPUID leaf 0x15, so the bit is also
+                # set on host.
+                "tsc_known_freq",
+            }
+
+            assert host_feats - guest_feats == expected_host_minus_guest
+            assert guest_feats - host_feats == expected_guest_minus_host
+
         case CpuModel.ARM_NEOVERSE_N1:
             expected_guest_minus_host = set()
             expected_host_minus_guest = set()