KVM: x86: implement MSR_IA32_TSX_CTRL effect on CPUID

Because KVM always emulates CPUID, the CPUID clear bit
(bit 1) of MSR_IA32_TSX_CTRL must be emulated "manually"
by the hypervisor when performing said emulation.

Right now neither kvm-intel.ko nor kvm-amd.ko implement
MSR_IA32_TSX_CTRL but this will change in the next patch.

Reviewed-by: Jim Mattson <[email protected]>
Tested-by: Jim Mattson <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Author: bonzini

arch/x86/include/asm/kvm_host.h

@@ -1357,6 +1357,7 @@ int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
 
 void kvm_enable_efer_bits(u64);
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
+int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data, bool host_initiated);
 int kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data);
 int kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data);
 int kvm_emulate_rdmsr(struct kvm_vcpu *vcpu);

arch/x86/kvm/cpuid.c

@@ -816,8 +816,6 @@ static int do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 func,
 	return __do_cpuid_func(entry, func, nent, maxnent);
 }
 
-#undef F
-
 struct kvm_cpuid_param {
 	u32 func;
 	bool (*qualifier)(const struct kvm_cpuid_param *param);
@@ -1015,6 +1013,12 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
 		*ebx = entry->ebx;
 		*ecx = entry->ecx;
 		*edx = entry->edx;
+		if (function == 7 && index == 0) {
+			u64 data;
+		        if (!__kvm_get_msr(vcpu, MSR_IA32_TSX_CTRL, &data, true) &&
+			    (data & TSX_CTRL_CPUID_CLEAR))
+				*ebx &= ~(F(RTM) | F(HLE));
+		}
 	} else {
 		*eax = *ebx = *ecx = *edx = 0;
 		/*

arch/x86/kvm/x86.c

@@ -1484,8 +1484,8 @@ static int __kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data,
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-static int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
-			 bool host_initiated)
+int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
+		  bool host_initiated)
 {
 	struct msr_data msr;
 	int ret;