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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/svm: Alias the VMCB segment registers as an array
commit c9d7c5e29e2560e7f2d0ca50109d005efb2e44f2
Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Jun 30 12:24:19 2017 +0000
Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Jul 27 16:25:15 2017 +0100
x86/svm: Alias the VMCB segment registers as an array
This allows svm_{get,set}_segment_register() to access the user segments by
array index, as the x86_seg_* constants match the hardware encoding.
While making this alteration, add some newlines for clarity, switch an int
for
a bool, and make the functions fail safe in a release build, rather than
crashing Xen.
Bloat-o-meter reports some modest improvements:
add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-130 (-130)
function old new delta
svm_set_segment_register 662 653 -9
svm_get_segment_register 409 288 -121
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
xen/arch/x86/hvm/svm/svm.c | 76 ++++++++++++++++++--------------------
xen/include/asm-x86/hvm/svm/vmcb.h | 17 ++++++---
2 files changed, 47 insertions(+), 46 deletions(-)
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 244da12..0dc9442 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -634,43 +634,39 @@ static void svm_get_segment_register(struct vcpu *v, enum
x86_segment seg,
switch ( seg )
{
- case x86_seg_cs:
- *reg = vmcb->cs;
- break;
- case x86_seg_ds:
- *reg = vmcb->ds;
- break;
- case x86_seg_es:
- *reg = vmcb->es;
- break;
- case x86_seg_fs:
- svm_sync_vmcb(v);
- *reg = vmcb->fs;
- break;
- case x86_seg_gs:
+ case x86_seg_fs ... x86_seg_gs:
svm_sync_vmcb(v);
- *reg = vmcb->gs;
- break;
- case x86_seg_ss:
- *reg = vmcb->ss;
- reg->dpl = vmcb_get_cpl(vmcb);
+
+ /* Fallthrough. */
+ case x86_seg_es ... x86_seg_ds:
+ *reg = vmcb->sreg[seg];
+
+ if ( seg == x86_seg_ss )
+ reg->dpl = vmcb_get_cpl(vmcb);
break;
+
case x86_seg_tr:
svm_sync_vmcb(v);
*reg = vmcb->tr;
break;
+
case x86_seg_gdtr:
*reg = vmcb->gdtr;
break;
+
case x86_seg_idtr:
*reg = vmcb->idtr;
break;
+
case x86_seg_ldtr:
svm_sync_vmcb(v);
*reg = vmcb->ldtr;
break;
+
default:
- BUG();
+ ASSERT_UNREACHABLE();
+ domain_crash(v->domain);
+ *reg = (struct segment_register){};
}
}
@@ -678,7 +674,7 @@ static void svm_set_segment_register(struct vcpu *v, enum
x86_segment seg,
struct segment_register *reg)
{
struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
- int sync = 0;
+ bool sync = false;
ASSERT((v == current) || !vcpu_runnable(v));
@@ -690,18 +686,23 @@ static void svm_set_segment_register(struct vcpu *v, enum
x86_segment seg,
case x86_seg_ss: /* cpl */
vmcb->cleanbits.fields.seg = 0;
break;
+
case x86_seg_gdtr:
case x86_seg_idtr:
vmcb->cleanbits.fields.dt = 0;
break;
+
case x86_seg_fs:
case x86_seg_gs:
case x86_seg_tr:
case x86_seg_ldtr:
sync = (v == current);
break;
+
default:
- break;
+ ASSERT_UNREACHABLE();
+ domain_crash(v->domain);
+ return;
}
if ( sync )
@@ -709,41 +710,36 @@ static void svm_set_segment_register(struct vcpu *v, enum
x86_segment seg,
switch ( seg )
{
- case x86_seg_cs:
- vmcb->cs = *reg;
- break;
- case x86_seg_ds:
- vmcb->ds = *reg;
- break;
- case x86_seg_es:
- vmcb->es = *reg;
- break;
- case x86_seg_fs:
- vmcb->fs = *reg;
- break;
- case x86_seg_gs:
- vmcb->gs = *reg;
- break;
case x86_seg_ss:
- vmcb->ss = *reg;
vmcb_set_cpl(vmcb, reg->dpl);
+
+ /* Fallthrough */
+ case x86_seg_es ... x86_seg_cs:
+ case x86_seg_ds ... x86_seg_gs:
+ vmcb->sreg[seg] = *reg;
break;
+
case x86_seg_tr:
vmcb->tr = *reg;
break;
+
case x86_seg_gdtr:
vmcb->gdtr.base = reg->base;
vmcb->gdtr.limit = reg->limit;
break;
+
case x86_seg_idtr:
vmcb->idtr.base = reg->base;
vmcb->idtr.limit = reg->limit;
break;
+
case x86_seg_ldtr:
vmcb->ldtr = *reg;
break;
- default:
- BUG();
+
+ case x86_seg_none:
+ ASSERT_UNREACHABLE();
+ break;
}
if ( sync )
diff --git a/xen/include/asm-x86/hvm/svm/vmcb.h
b/xen/include/asm-x86/hvm/svm/vmcb.h
index fa0d3e2..ec22d91 100644
--- a/xen/include/asm-x86/hvm/svm/vmcb.h
+++ b/xen/include/asm-x86/hvm/svm/vmcb.h
@@ -435,12 +435,17 @@ struct vmcb_struct {
u8 guest_ins[15]; /* offset 0xD1 */
u64 res10a[100]; /* offset 0xE0 pad to save area */
- struct segment_register es; /* offset 0x400 - cleanbit 8 */
- struct segment_register cs; /* cleanbit 8 */
- struct segment_register ss; /* cleanbit 8 */
- struct segment_register ds; /* cleanbit 8 */
- struct segment_register fs;
- struct segment_register gs;
+ union {
+ struct segment_register sreg[6];
+ struct {
+ struct segment_register es; /* offset 0x400 - cleanbit 8 */
+ struct segment_register cs; /* cleanbit 8 */
+ struct segment_register ss; /* cleanbit 8 */
+ struct segment_register ds; /* cleanbit 8 */
+ struct segment_register fs;
+ struct segment_register gs;
+ };
+ };
struct segment_register gdtr; /* cleanbit 7 */
struct segment_register ldtr;
struct segment_register idtr; /* cleanbit 7 */
--
generated by git-patchbot for /home/xen/git/xen.git#master
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