[PATCH v8 10/10] KVM: nVMX: Use macros and #defines in vmx_restore_vmx_misc()

Sean Christopherson
2024-06-05T23:19:41Z

From: Xin Li <xin3.li@intel.com>

Use macros in vmx_restore_vmx_misc() instead of open coding everything
using BIT_ULL() and GENMASK_ULL(). Opportunistically split feature bits
and reserved bits into separate variables, and add a comment explaining
the subset logic (it's not immediately obvious that the set of feature
bits is NOT the set of _supported_ feature bits).

Cc: Shan Kang <shan.kang@intel.com>
Cc: Kai Huang <kai.huang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
[sean: split to separate patch, write changelog, drop #defines]
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/nested.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 623e8fcbf427..4e3a2303fd9c 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1344,16 +1344,29 @@ vmx_restore_control_msr(struct vcpu_vmx *vmx, u32 msr_index, u64 data)

static int vmx_restore_vmx_misc(struct vcpu_vmx *vmx, u64 data)
{
- const u64 feature_and_reserved_bits =
- /* feature */
- BIT_ULL(5) | GENMASK_ULL(8, 6) | BIT_ULL(14) | BIT_ULL(15) |
- BIT_ULL(28) | BIT_ULL(29) | BIT_ULL(30) |
- /* reserved */
- GENMASK_ULL(13, 9) | BIT_ULL(31);
+ const u64 feature_bits = VMX_MISC_SAVE_EFER_LMA |
+ VMX_MISC_ACTIVITY_HLT |
+ VMX_MISC_ACTIVITY_SHUTDOWN |
+ VMX_MISC_ACTIVITY_WAIT_SIPI |
+ VMX_MISC_INTEL_PT |
+ VMX_MISC_RDMSR_IN_SMM |
+ VMX_MISC_VMWRITE_SHADOW_RO_FIELDS |
+ VMX_MISC_VMXOFF_BLOCK_SMI |
+ VMX_MISC_ZERO_LEN_INS;
+
+ const u64 reserved_bits = BIT_ULL(31) | GENMASK_ULL(13, 9);
+
u64 vmx_misc = vmx_control_msr(vmcs_config.nested.misc_low,
vmcs_config.nested.misc_high);

- if (!is_bitwise_subset(vmx_misc, data, feature_and_reserved_bits))
+ BUILD_BUG_ON(feature_bits & reserved_bits);
+
+ /*
+ * The incoming value must not set feature bits or reserved bits that
+ * aren't allowed/supported by KVM. Fields, i.e. multi-bit values, are
+ * explicitly checked below.
+ */
+ if (!is_bitwise_subset(vmx_misc, data, feature_bits | reserved_bits))
return -EINVAL;

if ((vmx->nested.msrs.pinbased_ctls_high &
--
2.45.1.467.gbab1589fc0-goog