Author: jhb
Date: Tue May 27 19:04:38 2014
New Revision: 266765
URL: http://svnweb.freebsd.org/changeset/base/266765
Log:
- Rework the XSAVE/XRSTOR emulation to only expose XCR0 features to the
guest for which the rules regarding xsetbv emulation are known. In
particular future extensions like AVX-512 have interdependencies among
feature bits that could allow a guest to trigger a GP# in the host with
the current approach of allowing anything the host supports.
- Add proper checking of Intel MPX and AVX-512 XSAVE features in the
xsetbv emulation and allow these features to be exposed to the guest if
they are enabled in the host.
- Expose a subset of known-safe features from leaf 0 of the structured
extended features to guests if they are supported on the host including
RDFSBASE/RDGSBASE, BMI1/2, AVX2, AVX-512, HLE, ERMS, and RTM. Aside
from AVX-512, these features are all new instructions available for use
in ring 3 with no additional hypervisor changes needed.
Reviewed by: neel
Modified:
head/sys/amd64/vmm/intel/vmx.c
head/sys/amd64/vmm/vmm_host.c
head/sys/amd64/vmm/x86.c
Modified: head/sys/amd64/vmm/intel/vmx.c
==============================================================================
--- head/sys/amd64/vmm/intel/vmx.c Tue May 27 19:02:25 2014
(r266764)
+++ head/sys/amd64/vmm/intel/vmx.c Tue May 27 19:04:38 2014
(r266765)
@@ -1380,8 +1380,30 @@ vmx_emulate_xsetbv(struct vmx *vmx, int
return (HANDLED);
}
- if ((xcrval & (XFEATURE_ENABLED_AVX | XFEATURE_ENABLED_SSE)) ==
- XFEATURE_ENABLED_AVX) {
+ /* AVX (YMM_Hi128) requires SSE. */
+ if (xcrval & XFEATURE_ENABLED_AVX &&
+ (xcrval & XFEATURE_AVX) != XFEATURE_AVX) {
+ vm_inject_gp(vmx->vm, vcpu);
+ return (HANDLED);
+ }
+
+ /*
+ * AVX512 requires base AVX (YMM_Hi128) as well as OpMask,
+ * ZMM_Hi256, and Hi16_ZMM.
+ */
+ if (xcrval & XFEATURE_AVX512 &&
+ (xcrval & (XFEATURE_AVX512 | XFEATURE_AVX)) !=
+ (XFEATURE_AVX512 | XFEATURE_AVX)) {
+ vm_inject_gp(vmx->vm, vcpu);
+ return (HANDLED);
+ }
+
+ /*
+ * Intel MPX requires both bound register state flags to be
+ * set.
+ */
+ if (((xcrval & XFEATURE_ENABLED_BNDREGS) != 0) !=
+ ((xcrval & XFEATURE_ENABLED_BNDCSR) != 0)) {
vm_inject_gp(vmx->vm, vcpu);
return (HANDLED);
}
Modified: head/sys/amd64/vmm/vmm_host.c
==============================================================================
--- head/sys/amd64/vmm/vmm_host.c Tue May 27 19:02:25 2014
(r266764)
+++ head/sys/amd64/vmm/vmm_host.c Tue May 27 19:04:38 2014
(r266765)
@@ -66,11 +66,16 @@ vmm_host_state_init(void)
* XSAVE. Only permit a guest to use XSAVE features supported
* by the host. This ensures that the FPU state used by the
* guest is always a subset of the saved guest FPU state.
+ *
+ * In addition, only permit known XSAVE features where the
+ * rules for which features depend on other features is known
+ * to properly emulate xsetbv.
*/
if (vmm_host_cr4 & CR4_XSAVE) {
vmm_xsave_limits.xsave_enabled = 1;
vmm_host_xcr0 = rxcr(0);
- vmm_xsave_limits.xcr0_allowed = vmm_host_xcr0;
+ vmm_xsave_limits.xcr0_allowed = vmm_host_xcr0 &
+ (XFEATURE_AVX | XFEATURE_MPX | XFEATURE_AVX512);
cpuid_count(0xd, 0x0, regs);
vmm_xsave_limits.xsave_max_size = regs[1];
Modified: head/sys/amd64/vmm/x86.c
==============================================================================
--- head/sys/amd64/vmm/x86.c Tue May 27 19:02:25 2014 (r266764)
+++ head/sys/amd64/vmm/x86.c Tue May 27 19:04:38 2014 (r266765)
@@ -241,6 +241,26 @@ x86_emulate_cpuid(struct vm *vm, int vcp
/* leaf 0 */
if (*ecx == 0) {
+ cpuid_count(*eax, *ecx, regs);
+
+ /* Only leaf 0 is supported */
+ regs[0] = 0;
+
+ /*
+ * Expose known-safe features.
+ */
+ regs[1] &= (CPUID_STDEXT_FSGSBASE |
+ CPUID_STDEXT_BMI1 | CPUID_STDEXT_HLE |
+ CPUID_STDEXT_AVX2 | CPUID_STDEXT_BMI2 |
+ CPUID_STDEXT_ERMS | CPUID_STDEXT_RTM |
+ CPUID_STDEXT_AVX512F |
+ CPUID_STDEXT_AVX512PF |
+ CPUID_STDEXT_AVX512ER |
+ CPUID_STDEXT_AVX512CD);
+ regs[2] = 0;
+ regs[3] = 0;
+
+ /* Advertise INVPCID if it is enabled. */
error = vm_get_capability(vm, vcpu_id,
VM_CAP_ENABLE_INVPCID, &enable_invpcid);
if (error == 0 && enable_invpcid)
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
