KVM: VMX: Implement PCID/INVPCID for guests with EPT
This patch handles PCID/INVPCID for guests.
Process-context identifiers (PCIDs) are a facility by which a logical processor
may cache information for multiple linear-address spaces so that the processor
may retain cached information when software switches to a different linear
address space. Refer to section 4.10.1 in IA32 Intel Software Developer's Manual
Volume 3A for details.
For guests with EPT, the PCID feature is enabled and INVPCID behaves as running
natively.
For guests without EPT, the PCID feature is disabled and INVPCID triggers #UD.
Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5c52a6d..c39b607 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -861,6 +861,12 @@
SECONDARY_EXEC_RDTSCP;
}
+static inline bool cpu_has_vmx_invpcid(void)
+{
+ return vmcs_config.cpu_based_2nd_exec_ctrl &
+ SECONDARY_EXEC_ENABLE_INVPCID;
+}
+
static inline bool cpu_has_virtual_nmis(void)
{
return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS;
@@ -1751,6 +1757,11 @@
return cpu_has_vmx_rdtscp();
}
+static bool vmx_invpcid_supported(void)
+{
+ return cpu_has_vmx_invpcid() && enable_ept;
+}
+
/*
* Swap MSR entry in host/guest MSR entry array.
*/
@@ -2470,7 +2481,8 @@
SECONDARY_EXEC_ENABLE_EPT |
SECONDARY_EXEC_UNRESTRICTED_GUEST |
SECONDARY_EXEC_PAUSE_LOOP_EXITING |
- SECONDARY_EXEC_RDTSCP;
+ SECONDARY_EXEC_RDTSCP |
+ SECONDARY_EXEC_ENABLE_INVPCID;
if (adjust_vmx_controls(min2, opt2,
MSR_IA32_VMX_PROCBASED_CTLS2,
&_cpu_based_2nd_exec_control) < 0)
@@ -3800,6 +3812,8 @@
if (!enable_ept) {
exec_control &= ~SECONDARY_EXEC_ENABLE_EPT;
enable_unrestricted_guest = 0;
+ /* Enable INVPCID for non-ept guests may cause performance regression. */
+ exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
}
if (!enable_unrestricted_guest)
exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;
@@ -6550,6 +6564,23 @@
}
}
}
+
+ exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
+ /* Exposing INVPCID only when PCID is exposed */
+ best = kvm_find_cpuid_entry(vcpu, 0x7, 0);
+ if (vmx_invpcid_supported() &&
+ best && (best->ecx & bit(X86_FEATURE_INVPCID)) &&
+ guest_cpuid_has_pcid(vcpu)) {
+ exec_control |= SECONDARY_EXEC_ENABLE_INVPCID;
+ vmcs_write32(SECONDARY_VM_EXEC_CONTROL,
+ exec_control);
+ } else {
+ exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
+ vmcs_write32(SECONDARY_VM_EXEC_CONTROL,
+ exec_control);
+ if (best)
+ best->ecx &= ~bit(X86_FEATURE_INVPCID);
+ }
}
static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
@@ -7284,6 +7315,7 @@
.cpuid_update = vmx_cpuid_update,
.rdtscp_supported = vmx_rdtscp_supported,
+ .invpcid_supported = vmx_invpcid_supported,
.set_supported_cpuid = vmx_set_supported_cpuid,