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* [PATCH for-4.9] x86/vmx: Shorten vmx_{get, set}_segment_register() for user segments
@ 2016-10-26 13:15 Andrew Cooper
  2016-10-26 13:40 ` Jan Beulich
  2016-11-16 13:42 ` Andrew Cooper
  0 siblings, 2 replies; 5+ messages in thread
From: Andrew Cooper @ 2016-10-26 13:15 UTC (permalink / raw)
  To: Xen-devel; +Cc: Andrew Cooper, Kevin Tian, Jun Nakajima, Jan Beulich

The x86_segment enumeration matches hardware SReg encoding, which can be used
to calculate the appropriate VMCS fields, rather than open coding every
instance.

This reduces the size of the switch statement, and the number of embedded BUG
frames from the __vm{read,write}() calls.  In the unlikely case that a call
does fault, the field can unambiguously be retrieved from the GPR state
printed.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Jun Nakajima <jun.nakajima@intel.com>
CC: Kevin Tian <kevin.tian@intel.com>
---
 xen/arch/x86/hvm/vmx/vmx.c         | 80 +++++---------------------------------
 xen/include/asm-x86/hvm/vmx/vmcs.h |  4 ++
 2 files changed, 14 insertions(+), 70 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 4d30eae..459f9cd 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -969,41 +969,11 @@ void vmx_get_segment_register(struct vcpu *v, enum x86_segment seg,
 
     switch ( seg )
     {
-    case x86_seg_cs:
-        __vmread(GUEST_CS_SELECTOR, &sel);
-        __vmread(GUEST_CS_LIMIT,    &limit);
-        __vmread(GUEST_CS_BASE,     &reg->base);
-        __vmread(GUEST_CS_AR_BYTES, &attr);
-        break;
-    case x86_seg_ds:
-        __vmread(GUEST_DS_SELECTOR, &sel);
-        __vmread(GUEST_DS_LIMIT,    &limit);
-        __vmread(GUEST_DS_BASE,     &reg->base);
-        __vmread(GUEST_DS_AR_BYTES, &attr);
-        break;
-    case x86_seg_es:
-        __vmread(GUEST_ES_SELECTOR, &sel);
-        __vmread(GUEST_ES_LIMIT,    &limit);
-        __vmread(GUEST_ES_BASE,     &reg->base);
-        __vmread(GUEST_ES_AR_BYTES, &attr);
-        break;
-    case x86_seg_fs:
-        __vmread(GUEST_FS_SELECTOR, &sel);
-        __vmread(GUEST_FS_LIMIT,    &limit);
-        __vmread(GUEST_FS_BASE,     &reg->base);
-        __vmread(GUEST_FS_AR_BYTES, &attr);
-        break;
-    case x86_seg_gs:
-        __vmread(GUEST_GS_SELECTOR, &sel);
-        __vmread(GUEST_GS_LIMIT,    &limit);
-        __vmread(GUEST_GS_BASE,     &reg->base);
-        __vmread(GUEST_GS_AR_BYTES, &attr);
-        break;
-    case x86_seg_ss:
-        __vmread(GUEST_SS_SELECTOR, &sel);
-        __vmread(GUEST_SS_LIMIT,    &limit);
-        __vmread(GUEST_SS_BASE,     &reg->base);
-        __vmread(GUEST_SS_AR_BYTES, &attr);
+    case x86_seg_es ... x86_seg_gs:
+        __vmread(GUEST_SEG_SELECTOR(seg), &sel);
+        __vmread(GUEST_SEG_LIMIT(seg),    &limit);
+        __vmread(GUEST_SEG_BASE(seg),     &reg->base);
+        __vmread(GUEST_SEG_AR_BYTES(seg), &attr);
         break;
     case x86_seg_tr:
         __vmread(GUEST_TR_SELECTOR, &sel);
@@ -1131,41 +1101,11 @@ static void vmx_set_segment_register(struct vcpu *v, enum x86_segment seg,
 
     switch ( seg )
     {
-    case x86_seg_cs:
-        __vmwrite(GUEST_CS_SELECTOR, sel);
-        __vmwrite(GUEST_CS_LIMIT, limit);
-        __vmwrite(GUEST_CS_BASE, base);
-        __vmwrite(GUEST_CS_AR_BYTES, attr);
-        break;
-    case x86_seg_ds:
-        __vmwrite(GUEST_DS_SELECTOR, sel);
-        __vmwrite(GUEST_DS_LIMIT, limit);
-        __vmwrite(GUEST_DS_BASE, base);
-        __vmwrite(GUEST_DS_AR_BYTES, attr);
-        break;
-    case x86_seg_es:
-        __vmwrite(GUEST_ES_SELECTOR, sel);
-        __vmwrite(GUEST_ES_LIMIT, limit);
-        __vmwrite(GUEST_ES_BASE, base);
-        __vmwrite(GUEST_ES_AR_BYTES, attr);
-        break;
-    case x86_seg_fs:
-        __vmwrite(GUEST_FS_SELECTOR, sel);
-        __vmwrite(GUEST_FS_LIMIT, limit);
-        __vmwrite(GUEST_FS_BASE, base);
-        __vmwrite(GUEST_FS_AR_BYTES, attr);
-        break;
-    case x86_seg_gs:
-        __vmwrite(GUEST_GS_SELECTOR, sel);
-        __vmwrite(GUEST_GS_LIMIT, limit);
-        __vmwrite(GUEST_GS_BASE, base);
-        __vmwrite(GUEST_GS_AR_BYTES, attr);
-        break;
-    case x86_seg_ss:
-        __vmwrite(GUEST_SS_SELECTOR, sel);
-        __vmwrite(GUEST_SS_LIMIT, limit);
-        __vmwrite(GUEST_SS_BASE, base);
-        __vmwrite(GUEST_SS_AR_BYTES, attr);
+    case x86_seg_es ... x86_seg_gs:
+        __vmwrite(GUEST_SEG_SELECTOR(seg), sel);
+        __vmwrite(GUEST_SEG_LIMIT(seg),    limit);
+        __vmwrite(GUEST_SEG_BASE(seg),     base);
+        __vmwrite(GUEST_SEG_AR_BYTES(seg), attr);
         break;
     case x86_seg_tr:
         __vmwrite(GUEST_TR_SELECTOR, sel);
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h b/xen/include/asm-x86/hvm/vmx/vmcs.h
index 997f4f5..894093d 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -420,6 +420,7 @@ enum vmcs_field {
     VIRTUAL_PROCESSOR_ID            = 0x00000000,
     POSTED_INTR_NOTIFICATION_VECTOR = 0x00000002,
     EPTP_INDEX                      = 0x00000004,
+#define GUEST_SEG_SELECTOR(sel) (GUEST_ES_SELECTOR + (sel) * 2) /* ES ... GS */
     GUEST_ES_SELECTOR               = 0x00000800,
     GUEST_CS_SELECTOR               = 0x00000802,
     GUEST_SS_SELECTOR               = 0x00000804,
@@ -496,6 +497,7 @@ enum vmcs_field {
     IDT_VECTORING_ERROR_CODE        = 0x0000440a,
     VM_EXIT_INSTRUCTION_LEN         = 0x0000440c,
     VMX_INSTRUCTION_INFO            = 0x0000440e,
+#define GUEST_SEG_LIMIT(sel) (GUEST_ES_LIMIT + (sel) * 2) /* ES ... GS */
     GUEST_ES_LIMIT                  = 0x00004800,
     GUEST_CS_LIMIT                  = 0x00004802,
     GUEST_SS_LIMIT                  = 0x00004804,
@@ -506,6 +508,7 @@ enum vmcs_field {
     GUEST_TR_LIMIT                  = 0x0000480e,
     GUEST_GDTR_LIMIT                = 0x00004810,
     GUEST_IDTR_LIMIT                = 0x00004812,
+#define GUEST_SEG_AR_BYTES(sel) (GUEST_ES_AR_BYTES + (sel) * 2) /* ES ... GS */
     GUEST_ES_AR_BYTES               = 0x00004814,
     GUEST_CS_AR_BYTES               = 0x00004816,
     GUEST_SS_AR_BYTES               = 0x00004818,
@@ -531,6 +534,7 @@ enum vmcs_field {
     GUEST_CR0                       = 0x00006800,
     GUEST_CR3                       = 0x00006802,
     GUEST_CR4                       = 0x00006804,
+#define GUEST_SEG_BASE(sel) (GUEST_ES_BASE + (sel) * 2) /* ES ... GS */
     GUEST_ES_BASE                   = 0x00006806,
     GUEST_CS_BASE                   = 0x00006808,
     GUEST_SS_BASE                   = 0x0000680a,
-- 
2.1.4


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Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2016-10-26 13:15 [PATCH for-4.9] x86/vmx: Shorten vmx_{get, set}_segment_register() for user segments Andrew Cooper
2016-10-26 13:40 ` Jan Beulich
2016-11-16 13:42 ` Andrew Cooper
2016-11-17  5:10   ` Tian, Kevin
2016-11-17 11:59     ` Andrew Cooper

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