kvm: vmx: Add IA32_FLUSH_CMD guest support

Expose IA32_FLUSH_CMD to the guest if the guest CPUID enumerates
support for this MSR. As with IA32_PRED_CMD, permission for
unintercepted writes to this MSR will be granted to the guest after
the first non-zero write.

Co-developed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20230201132905.549148-2-eesposit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 1bc2b80273c97f92947c4ffd649ceb2426fb4fa5..f63b28f46a713313d911f643ea0dba342cf35240 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -654,6 +654,9 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
        nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
                                         MSR_IA32_PRED_CMD, MSR_TYPE_W);
 
+       nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
+                                        MSR_IA32_FLUSH_CMD, MSR_TYPE_W);
+
        kvm_vcpu_unmap(vcpu, &vmx->nested.msr_bitmap_map, false);
 
        vmx->nested.force_msr_bitmap_recalc = false;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f777509ecf17112b9afe8d40c6f78accb7d95212..d7bf14abdba1df6e91df8e96e23b935fe788b896 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2133,6 +2133,39 @@ static u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated
        return debugctl;
 }
 
+static int vmx_set_msr_ia32_cmd(struct kvm_vcpu *vcpu,
+                               struct msr_data *msr_info,
+                               bool guest_has_feat, u64 cmd,
+                               int x86_feature_bit)
+{
+       if (!msr_info->host_initiated && !guest_has_feat)
+               return 1;
+
+       if (!(msr_info->data & ~cmd))
+               return 1;
+       if (!boot_cpu_has(x86_feature_bit))
+               return 1;
+       if (!msr_info->data)
+               return 0;
+
+       wrmsrl(msr_info->index, cmd);
+
+       /*
+        * For non-nested:
+        * When it's written (to non-zero) for the first time, pass
+        * it through.
+        *
+        * For nested:
+        * The handling of the MSR bitmap for L2 guests is done in
+        * nested_vmx_prepare_msr_bitmap. We should not touch the
+        * vmcs02.msr_bitmap here since it gets completely overwritten
+        * in the merging.
+        */
+       vmx_disable_intercept_for_msr(vcpu, msr_info->index, MSR_TYPE_W);
+
+       return 0;
+}
+
 /*
  * Writes msr value into the appropriate "register".
  * Returns 0 on success, non-0 otherwise.
@@ -2286,31 +2319,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                        return 1;
                goto find_uret_msr;
        case MSR_IA32_PRED_CMD:
-               if (!msr_info->host_initiated &&
-                   !guest_has_pred_cmd_msr(vcpu))
-                       return 1;
-
-               if (data & ~PRED_CMD_IBPB)
-                       return 1;
-               if (!boot_cpu_has(X86_FEATURE_IBPB))
-                       return 1;
-               if (!data)
-                       break;
-
-               wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);
-
-               /*
-                * For non-nested:
-                * When it's written (to non-zero) for the first time, pass
-                * it through.
-                *
-                * For nested:
-                * The handling of the MSR bitmap for L2 guests is done in
-                * nested_vmx_prepare_msr_bitmap. We should not touch the
-                * vmcs02.msr_bitmap here since it gets completely overwritten
-                * in the merging.
-                */
-               vmx_disable_intercept_for_msr(vcpu, MSR_IA32_PRED_CMD, MSR_TYPE_W);
+               ret = vmx_set_msr_ia32_cmd(vcpu, msr_info,
+                                          guest_has_pred_cmd_msr(vcpu),
+                                          PRED_CMD_IBPB,
+                                          X86_FEATURE_IBPB);
+               break;
+       case MSR_IA32_FLUSH_CMD:
+               ret = vmx_set_msr_ia32_cmd(vcpu, msr_info,
+                                          guest_cpuid_has(vcpu, X86_FEATURE_FLUSH_L1D),
+                                          L1D_FLUSH,
+                                          X86_FEATURE_FLUSH_L1D);
                break;
        case MSR_IA32_CR_PAT:
                if (!kvm_pat_valid(data))