vmx: add new boot parameter to control PML enabling

A top level EPT parameter "ept=<options>" and a sub boolean "opt_pml_enabled"
are added to control PML. Other booleans can be further added for any other EPT
related features.

The document description for the new parameter is also added.

Signed-off-by: Kai Huang <kai.huang@linux.intel.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Kevin Tian <kevin.tian@intel.com>

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index 1dda1f0604b29816635b6edf91d4ff06c2e3bf09..4889e27626d43ba5339d71e6d7da6dbdec7c3aa7 100644 (file)
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -685,6 +685,21 @@ requirement can be relaxed.  This option is particularly useful for nested
 virtualization, to allow the L1 hypervisor to use EPT even if the L0 hypervisor
 does not provide VM\_ENTRY\_LOAD\_GUEST\_PAT.
 
+### ept (Intel)
+> `= List of ( pml<boolean> )`
+
+> Default: `false`
+
+Controls EPT related features. Currently only Page Modification Logging (PML) is
+the controllable feature as boolean type.
+
+PML is a new hardware feature in Intel's Broadwell Server and further platforms
+which reduces hypervisor overhead of log-dirty mechanism by automatically
+recording GPAs (guest physical addresses) when guest memory gets dirty, and
+therefore significantly reducing number of EPT violation caused by write
+protection of guest memory, which is a necessity to implement log-dirty
+mechanism before PML.
+
 ### gdb
 > `= <baud>[/<clock_hz>][,DPS[,<io-base>[,<irq>[,<port-bdf>[,<bridge-bdf>]]]] | pci | amt ] `
 

diff --git a/tools/tests/x86_emulator/test_x86_emulator.c b/tools/tests/x86_emulator/test_x86_emulator.c
index b789edf0cafc0549b6fbe1476a9394c59f9de325..1b78bf7e450f15eeed12d9fe73696e56ba963293 100644 (file)
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -288,7 +288,7 @@ int main(int argc, char **argv)
     rc = x86_emulate(&ctxt, &emulops);
     if ( (rc != X86EMUL_OKAY) || 
          (*res != 0x923456AA) || 
-         ((regs.eflags&0xad5) != 0xa91) ||
+         ((regs.eflags & 0xad5) != 0xa91) ||
          (regs.eax != 0xAABBCCAA) ||
          (regs.ecx != 0xFF) ||
          (regs.eip != (unsigned long)&instr[4]) )

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 8b98a9f52ec771235bcee8439b49e5e57e409033..0a9a1aafbb14dc478577a5aab89f907571bc8b7c 100644 (file)
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -64,6 +64,36 @@ integer_param("ple_gap", ple_gap);
 static unsigned int __read_mostly ple_window = 4096;
 integer_param("ple_window", ple_window);
 
+static bool_t __read_mostly opt_pml_enabled = 0;
+
+/*
+ * The 'ept' parameter controls functionalities that depend on, or impact the
+ * EPT mechanism. Optional comma separated value may contain:
+ *
+ *  pml                 Enable PML
+ */
+static void __init parse_ept_param(char *s)
+{
+    char *ss;
+
+    do {
+        bool_t val = !!strncmp(s, "no-", 3);
+
+        if ( !val )
+            s += 3;
+
+        ss = strchr(s, ',');
+        if ( ss )
+            *ss = '\0';
+
+        if ( !strcmp(s, "pml") )
+            opt_pml_enabled = val;
+
+        s = ss + 1;
+    } while ( ss );
+}
+custom_param("ept", parse_ept_param);
+
 /* Dynamic (run-time adjusted) execution control flags. */
 u32 vmx_pin_based_exec_control __read_mostly;
 u32 vmx_cpu_based_exec_control __read_mostly;