[Xen-devel] [PATCH 7/8] x86/SVM: Introduce svm command line option

[Janakarajan Natarajan <Janakarajan.Natarajan@xxxxxxx>]

From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>

This patch introduces a new Xen command line option to enable/disable
SVM sub-options. Currently, it support sub-option "avic", which can
be used to enable/disable SVM AVIC feature.

Signed-off-by: Suavee Suthikulpant <suravee.suthikulpanit@xxxxxxx>
Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@xxxxxxx>
---
 docs/misc/xen-command-line.markdown | 16 ++++++++++++++++
 xen/arch/x86/hvm/svm/svm.c          | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/docs/misc/xen-command-line.markdown 
b/docs/misc/xen-command-line.markdown
index b353352adf..60a1005c42 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1730,6 +1730,22 @@ enforces the maximum theoretically necessary timeout of 
670ms. Any number
 is being interpreted as a custom timeout in milliseconds. Zero or boolean
 false disable the quirk workaround, which is also the default.
 
+### svm
+> `= List of [ avic ]`
+
+> Sub-options:
+
+> All sub-options are of boolean kind and can be prefixed with `no-` to
+> effect the inverse meaning.
+
+> `avic`
+
+> Default: `false`
+
+>> This option enables Advanced Virtual Interrupt Controller (AVIC),
+>> which is an extension of AMD Secure Virtual Machine (SVM) to virtualize
+>> local APIC for guest VM.
+
 ### sync\_console
 > `= <boolean>`
 
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index fdbe8e3008..0c5c26cce8 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -64,6 +64,16 @@
 #include <asm/monitor.h>
 #include <asm/xstate.h>
 
+static int parse_svm_param(const char *s);
+
+/*
+ * The 'svm' parameter en/dis-ables various SVM features.
+ * Optional comma separated value may contain:
+ *
+ *   avic - Enable SVM Advanced Virtual Interrupt Controller (AVIC)
+ */
+custom_param("svm", parse_svm_param);
+
 void svm_asm_do_resume(void);
 
 u32 svm_feature_flags;
@@ -89,6 +99,28 @@ static bool_t amd_erratum383_found __read_mostly;
 static uint64_t osvw_length, osvw_status;
 static DEFINE_SPINLOCK(osvw_lock);
 
+static int __init parse_svm_param(const char *s)
+{
+    char *ss;
+    int val;
+
+    do {
+        val = !!strncmp(s, "no-", 3);
+        if ( !val )
+            s += 3;
+
+        ss = strchr(s, ',');
+        if ( ss )
+            *ss = '\0';
+
+        if ( !strcmp(s, "avic") )
+            svm_avic = val;
+
+        s = ss + 1;
+    } while ( ss );
+
+    return 0;
+}
 /* Only crash the guest if the problem originates in kernel mode. */
 static void svm_crash_or_fault(struct vcpu *v)
 {
-- 
2.11.0


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