[Xen-devel] [PATCH RFC 02/14] xen: vmx: Added VMX SPP feature flags and VM-Execution Controls.

[Zhang Yi <yi.z.zhang@xxxxxxxxxxxxxxx>]

From: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx>

Add new secondary processor-based VM-execution control bit which
defined as "sub-page write permission", VMX Procbased MSR -
MSR_IA32_VMX_EXIT_CTLS bit 23 is the capability bit of SPP.
And VMX_SECONDARY_EXEC_CONTROL bit 23 is the enable bit of SPP.

Also we introduced a spp_enable parameter to control the
SPP is ON/OFF, Set the default is OFF as we are on the
way of enabling. we can add spp_enable=1 Xen boot cmdline
to enable Xen SPP.

Now SPP is active when the "Sub-page Write Protection"
in Secondary VM-Execution Control is set and enable the Xen
parameter by "spp_enable=1".

Signed-off-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmcs.c        | 14 ++++++++++++++
 xen/include/asm-x86/hvm/vmx/vmcs.h |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 8103b20..bee5d74 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -50,6 +50,9 @@ boolean_param("unrestricted_guest", 
opt_unrestricted_guest_enabled);
 static bool_t __read_mostly opt_apicv_enabled = 1;
 boolean_param("apicv", opt_apicv_enabled);
 
+static bool_t __read_mostly opt_spp_enabled = 0;
+boolean_param("spp_enable", opt_spp_enabled);
+
 /*
  * These two parameters are used to config the controls for Pause-Loop Exiting:
  * ple_gap:    upper bound on the amount of time between two successive
@@ -138,6 +141,7 @@ static void __init vmx_display_features(void)
     P(cpu_has_vmx_virt_exceptions, "Virtualisation Exceptions");
     P(cpu_has_vmx_pml, "Page Modification Logging");
     P(cpu_has_vmx_tsc_scaling, "TSC Scaling");
+    P(cpu_has_vmx_ept_spp, "EPT Sub-page Write Protection");
 #undef P
 
     if ( !printed )
@@ -243,6 +247,8 @@ static int vmx_init_vmcs_config(void)
             opt |= SECONDARY_EXEC_UNRESTRICTED_GUEST;
         if ( opt_pml_enabled )
             opt |= SECONDARY_EXEC_ENABLE_PML;
+        if ( opt_spp_enabled )
+            opt |= SECONDARY_EXEC_ENABLE_SPP;
 
         /*
          * "APIC Register Virtualization" and "Virtual Interrupt Delivery"
@@ -336,6 +342,14 @@ static int vmx_init_vmcs_config(void)
         _vmx_secondary_exec_control &= ~ SECONDARY_EXEC_PAUSE_LOOP_EXITING;
     }
 
+    /* SPP cannot be supported if EPT is not used */
+    if ( !(_vmx_secondary_exec_control & SECONDARY_EXEC_ENABLE_EPT) )
+        _vmx_secondary_exec_control &= ~SECONDARY_EXEC_ENABLE_SPP;
+
+    /* Turn off opt_spp_enabled if SPP feature is not present */
+    if ( !(_vmx_secondary_exec_control & SECONDARY_EXEC_ENABLE_SPP) )
+        opt_spp_enabled = 0;
+
     min = VM_EXIT_ACK_INTR_ON_EXIT;
     opt = VM_EXIT_SAVE_GUEST_PAT | VM_EXIT_LOAD_HOST_PAT |
           VM_EXIT_CLEAR_BNDCFGS;
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h 
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index e3cdfdf..139f590 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -235,6 +235,7 @@ extern u32 vmx_vmentry_control;
 #define SECONDARY_EXEC_ENABLE_PML               0x00020000
 #define SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS   0x00040000
 #define SECONDARY_EXEC_XSAVES                   0x00100000
+#define SECONDARY_EXEC_ENABLE_SPP               0x00800000
 #define SECONDARY_EXEC_TSC_SCALING              0x02000000
 extern u32 vmx_secondary_exec_control;
 
@@ -312,6 +313,8 @@ extern u64 vmx_ept_vpid_cap;
     (vmx_secondary_exec_control & SECONDARY_EXEC_XSAVES)
 #define cpu_has_vmx_tsc_scaling \
     (vmx_secondary_exec_control & SECONDARY_EXEC_TSC_SCALING)
+#define cpu_has_vmx_ept_spp \
+    (vmx_secondary_exec_control & SECONDARY_EXEC_ENABLE_SPP)
 
 #define VMCS_RID_TYPE_MASK              0x80000000
 
-- 
2.7.4


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