[RFC PATCH V2 03/11] KVM: VMX: Added VMX SPP feature flags and VM-Execution Controls.

[Zhang Yi]

Add new secondary processor-based VM-execution control bit which
defined as "sub-page write permission", same as VMX Procbased MSR,
bit 23 is the enable bit of SPP.

Also we introduced a enable_ept_spp parameter to control the
SPP is ON/OFF, Set the default is OFF as we are on the way of
enabling.

Now SPP is active when the "Sub-page Write Protection"
in Secondary VM-Execution Control is set and enable the kernel
parameter by "spp=on".

Signed-off-by: Zhang Yi <yi.z.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/vmx.h |  1 +
 arch/x86/kvm/vmx.c         | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index ade0f15..2aa088f 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -78,6 +78,7 @@
 #define SECONDARY_EXEC_RDSEED_EXITING		0x00010000
 #define SECONDARY_EXEC_ENABLE_PML               0x00020000
 #define SECONDARY_EXEC_XSAVES			0x00100000
+#define SECONDARY_EXEC_ENABLE_SPP		0x00800000
 #define SECONDARY_EXEC_TSC_SCALING              0x02000000
 
 #define PIN_BASED_EXT_INTR_MASK                 0x00000001
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4555077..f76d3fb 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -92,6 +92,9 @@ module_param_named(unrestricted_guest,
 static bool __read_mostly enable_ept_ad_bits = 1;
 module_param_named(eptad, enable_ept_ad_bits, bool, S_IRUGO);
 
+static bool __read_mostly enable_ept_spp;
+module_param_named(spp, enable_ept_spp, bool, S_IRUGO);
+
 static bool __read_mostly emulate_invalid_guest_state = true;
 module_param(emulate_invalid_guest_state, bool, S_IRUGO);
 
@@ -1941,6 +1944,11 @@ static inline bool cpu_has_vmx_pml(void)
 	return vmcs_config.cpu_based_2nd_exec_ctrl & SECONDARY_EXEC_ENABLE_PML;
 }
 
+static inline bool cpu_has_vmx_ept_spp(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl & SECONDARY_EXEC_ENABLE_SPP;
+}
+
 static inline bool cpu_has_vmx_tsc_scaling(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -4583,6 +4591,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_RDSEED_EXITING |
 			SECONDARY_EXEC_RDRAND_EXITING |
 			SECONDARY_EXEC_ENABLE_PML |
+			SECONDARY_EXEC_ENABLE_SPP |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC |
 			SECONDARY_EXEC_ENCLS_EXITING;
@@ -6486,6 +6495,9 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (!enable_ept_spp)
+		exec_control &= ~SECONDARY_EXEC_ENABLE_SPP;
+
 	if (vmx_xsaves_supported()) {
 		/* Exposing XSAVES only when XSAVE is exposed */
 		bool xsaves_enabled =
@@ -7927,6 +7939,9 @@ static __init int hardware_setup(void)
 	if (!cpu_has_vmx_unrestricted_guest() || !enable_ept)
 		enable_unrestricted_guest = 0;
 
+	if (!cpu_has_vmx_ept_spp() || !enable_ept)
+		enable_ept_spp = 0;
+
 	if (!cpu_has_vmx_flexpriority())
 		flexpriority_enabled = 0;
 
-- 
2.7.4