[PATCH v3 11/11] KVM:SVM: Enable INVPCID feature on AMD

Babu Moger
2020-07-28T23:39:09Z

The following intercept bit has been added to support VMEXIT
for INVPCID instruction:
Code Name Cause
A2h VMEXIT_INVPCID INVPCID instruction

The following bit has been added to the VMCB layout control area
to control intercept of INVPCID:
Byte Offset Bit(s) Function
14h 2 intercept INVPCID

Enable the interceptions when the the guest is running with shadow
page table enabled and handle the tlbflush based on the invpcid
instruction type.

For the guests with nested page table (NPT) support, the INVPCID
feature works as running it natively. KVM does not need to do any
special handling in this case.

AMD documentation for INVPCID feature is available at "AMD64
Architecture Programmer’s Manual Volume 2: System Programming,
Pub. 24593 Rev. 3.34(or later)"

The documentation can be obtained at the links below:
Link: https://www.amd.com/system/files/TechDocs/24593.pdf
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
arch/x86/include/uapi/asm/svm.h | 2 +
arch/x86/kvm/svm/svm.c | 64 +++++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)

diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
index 2e8a30f06c74..522d42dfc28c 100644
--- a/arch/x86/include/uapi/asm/svm.h
+++ b/arch/x86/include/uapi/asm/svm.h
@@ -76,6 +76,7 @@
#define SVM_EXIT_MWAIT_COND 0x08c
#define SVM_EXIT_XSETBV 0x08d
#define SVM_EXIT_RDPRU 0x08e
+#define SVM_EXIT_INVPCID 0x0a2
#define SVM_EXIT_NPF 0x400
#define SVM_EXIT_AVIC_INCOMPLETE_IPI 0x401
#define SVM_EXIT_AVIC_UNACCELERATED_ACCESS 0x402
@@ -171,6 +172,7 @@
{ SVM_EXIT_MONITOR, "monitor" }, \
{ SVM_EXIT_MWAIT, "mwait" }, \
{ SVM_EXIT_XSETBV, "xsetbv" }, \
+ { SVM_EXIT_INVPCID, "invpcid" }, \
{ SVM_EXIT_NPF, "npf" }, \
{ SVM_EXIT_AVIC_INCOMPLETE_IPI, "avic_incomplete_ipi" }, \
{ SVM_EXIT_AVIC_UNACCELERATED_ACCESS, "avic_unaccelerated_access" }, \
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 99cc9c285fe6..6b099e0b28c0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -813,6 +813,11 @@ static __init void svm_set_cpu_caps(void)
if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
boot_cpu_has(X86_FEATURE_AMD_SSBD))
kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
+
+ /* Enable INVPCID if both PCID and INVPCID enabled */
+ if (boot_cpu_has(X86_FEATURE_PCID) &&
+ boot_cpu_has(X86_FEATURE_INVPCID))
+ kvm_cpu_cap_set(X86_FEATURE_INVPCID);
}

static __init int svm_hardware_setup(void)
@@ -1099,6 +1104,18 @@ static void init_vmcb(struct vcpu_svm *svm)
clr_intercept(svm, INTERCEPT_PAUSE);
}

+ /*
+ * Intercept INVPCID instruction only if shadow page table is
+ * enabled. Interception is not required with nested page table
+ * enabled.
+ */
+ if (boot_cpu_has(X86_FEATURE_INVPCID)) {
+ if (!npt_enabled)
+ set_intercept(svm, INTERCEPT_INVPCID);
+ else
+ clr_intercept(svm, INTERCEPT_INVPCID);
+ }
+
if (kvm_vcpu_apicv_active(&svm->vcpu))
avic_init_vmcb(svm);

@@ -2715,6 +2732,43 @@ static int mwait_interception(struct vcpu_svm *svm)
return nop_interception(svm);
}

+static int invpcid_interception(struct vcpu_svm *svm)
+{
+ struct kvm_vcpu *vcpu = &svm->vcpu;
+ struct x86_exception e;
+ unsigned long type;
+ gva_t gva;
+ struct {
+ u64 pcid;
+ u64 gla;
+ } operand;
+
+ if (!guest_cpuid_has(vcpu, X86_FEATURE_INVPCID)) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 1;
+ }
+
+ /*
+ * For an INVPCID intercept:
+ * EXITINFO1 provides the linear address of the memory operand.
+ * EXITINFO2 provides the contents of the register operand.
+ */
+ type = svm->vmcb->control.exit_info_2;
+ gva = svm->vmcb->control.exit_info_1;
+
+ if (type > 3) {
+ kvm_inject_gp(vcpu, 0);
+ return 1;
+ }
+
+ if (kvm_read_guest_virt(vcpu, gva, &operand, sizeof(operand), &e)) {
+ kvm_inject_emulated_page_fault(vcpu, &e);
+ return 1;
+ }
+
+ return kvm_handle_invpcid(vcpu, type, operand.pcid, operand.gla);
+}
+
static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_READ_CR0] = cr_interception,
[SVM_EXIT_READ_CR3] = cr_interception,
@@ -2777,6 +2831,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_MWAIT] = mwait_interception,
[SVM_EXIT_XSETBV] = xsetbv_interception,
[SVM_EXIT_RDPRU] = rdpru_interception,
+ [SVM_EXIT_INVPCID] = invpcid_interception,
[SVM_EXIT_NPF] = npf_interception,
[SVM_EXIT_RSM] = rsm_interception,
[SVM_EXIT_AVIC_INCOMPLETE_IPI] = avic_incomplete_ipi_interception,
@@ -3562,6 +3617,15 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
svm->nrips_enabled = kvm_cpu_cap_has(X86_FEATURE_NRIPS) &&
guest_cpuid_has(&svm->vcpu, X86_FEATURE_NRIPS);

+ /* Check again if INVPCID interception if required */
+ if (boot_cpu_has(X86_FEATURE_INVPCID) &&
+ guest_cpuid_has(vcpu, X86_FEATURE_INVPCID)) {
+ if (!npt_enabled)
+ set_intercept(svm, INTERCEPT_INVPCID);
+ else
+ clr_intercept(svm, INTERCEPT_INVPCID);
+ }
+
if (!kvm_vcpu_apicv_active(vcpu))
return;