[PATCH 4.14 001/237] KVM: x86: emulate RDPID

Greg Kroah-Hartman
2020-02-27T13:52:28Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit fb6d4d340e0532032c808a9933eaaa7b8de435ab upstream.

This is encoded as F3 0F C7 /7 with a register argument. The register
argument is the second array in the group9 GroupDual, while F3 is the
fourth element of a Prefix.

Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/cpuid.c | 7 ++++++-
arch/x86/kvm/emulate.c | 22 +++++++++++++++++++++-
arch/x86/kvm/vmx.c | 15 +++++++++++++++
3 files changed, 42 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -291,13 +291,18 @@ static int __do_cpuid_ent_emulated(struc
{
switch (func) {
case 0:
- entry->eax = 1; /* only one leaf currently */
+ entry->eax = 7;
++*nent;
break;
case 1:
entry->ecx = F(MOVBE);
++*nent;
break;
+ case 7:
+ entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ if (index == 0)
+ entry->ecx = F(RDPID);
+ ++*nent;
default:
break;
}
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3539,6 +3539,16 @@ static int em_cwd(struct x86_emulate_ctx
return X86EMUL_CONTINUE;
}

+static int em_rdpid(struct x86_emulate_ctxt *ctxt)
+{
+ u64 tsc_aux = 0;
+
+ if (ctxt->ops->get_msr(ctxt, MSR_TSC_AUX, &tsc_aux))
+ return emulate_gp(ctxt, 0);
+ ctxt->dst.val = tsc_aux;
+ return X86EMUL_CONTINUE;
+}
+
static int em_rdtsc(struct x86_emulate_ctxt *ctxt)
{
u64 tsc = 0;
@@ -4431,10 +4441,20 @@ static const struct opcode group8[] = {
F(DstMem | SrcImmByte | Lock | PageTable, em_btc),
};

+/*
+ * The "memory" destination is actually always a register, since we come
+ * from the register case of group9.
+ */
+static const struct gprefix pfx_0f_c7_7 = {
+ N, N, N, II(DstMem | ModRM | Op3264 | EmulateOnUD, em_rdpid, rdtscp),
+};
+
+
static const struct group_dual group9 = { {
N, I(DstMem64 | Lock | PageTable, em_cmpxchg8b), N, N, N, N, N, N,
}, {
- N, N, N, N, N, N, N, N,
+ N, N, N, N, N, N, N,
+ GP(0, &pfx_0f_c7_7),
} };

static const struct opcode group11[] = {
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -12322,6 +12322,21 @@ static int vmx_check_intercept(struct kv
struct x86_instruction_info *info,
enum x86_intercept_stage stage)
{
+ struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+ struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt;
+
+ /*
+ * RDPID causes #UD if disabled through secondary execution controls.
+ * Because it is marked as EmulateOnUD, we need to intercept it here.
+ */
+ if (info->intercept == x86_intercept_rdtscp &&
+ !nested_cpu_has2(vmcs12, SECONDARY_EXEC_RDTSCP)) {
+ ctxt->exception.vector = UD_VECTOR;
+ ctxt->exception.error_code_valid = false;
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+
+ /* TODO: check more intercepts... */
return X86EMUL_CONTINUE;
}