[src/trunk]: src/sys/dev/nvmm/x86 Initialize the guest TSC to zero at VCPU cr...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1ace3b0bc3ad
branches:  trunk
changeset: 448949:1ace3b0bc3ad
user:      maxv <maxv%NetBSD.org@localhost>
date:      Fri Feb 15 13:17:05 2019 +0000

description:
Initialize the guest TSC to zero at VCPU creation time, and handle guest
writes to MSR_TSC at run time.

This is imprecise, because the hardware does not provide a way to preserve
the TSC during #VMEXITs, but that's fine enough.

diffstat:

 sys/dev/nvmm/x86/nvmm_x86_svm.c |  18 +++++++++++++-----
 sys/dev/nvmm/x86/nvmm_x86_vmx.c |  15 +++++++++++----
 2 files changed, 24 insertions(+), 9 deletions(-)

diffs (103 lines):

diff -r 126d69463098 -r 1ace3b0bc3ad sys/dev/nvmm/x86/nvmm_x86_svm.c
--- a/sys/dev/nvmm/x86/nvmm_x86_svm.c   Fri Feb 15 08:54:01 2019 +0000
+++ b/sys/dev/nvmm/x86/nvmm_x86_svm.c   Fri Feb 15 13:17:05 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm_x86_svm.c,v 1.23 2019/02/14 14:30:20 maxv Exp $   */
+/*     $NetBSD: nvmm_x86_svm.c,v 1.24 2019/02/15 13:17:05 maxv Exp $   */
 
 /*
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvmm_x86_svm.c,v 1.23 2019/02/14 14:30:20 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvmm_x86_svm.c,v 1.24 2019/02/15 13:17:05 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -46,6 +46,7 @@
 #include <x86/specialreg.h>
 #include <x86/pmap.h>
 #include <x86/dbregs.h>
+#include <x86/cpu_counter.h>
 #include <machine/cpuvar.h>
 
 #include <dev/nvmm/nvmm.h>
@@ -965,7 +966,14 @@
                                cpudata->tlb_want_flush = true;
                        }
                        vmcb->state.efer = exit->u.msr.val | EFER_SVME;
-                       vmcb->ctrl.vmcb_clean &= ~VMCB_CTRL_VMCB_CLEAN_CR;
+                       svm_vmcb_cache_flush(vmcb, VMCB_CTRL_VMCB_CLEAN_CR);
+                       goto handled;
+               }
+               if (exit->u.msr.msr == MSR_TSC) {
+                       cpudata->tsc_offset = exit->u.msr.val - cpu_counter();
+                       vmcb->ctrl.tsc_offset = cpudata->tsc_offset +
+                           curcpu()->ci_data.cpu_cc_skew;
+                       svm_vmcb_cache_flush(vmcb, VMCB_CTRL_VMCB_CLEAN_I);
                        goto handled;
                }
                for (i = 0; i < __arraycount(msr_ignore_list); i++) {
@@ -1582,8 +1590,8 @@
        cpudata->gfpu.xsh_xstate_bv = svm_xcr0_mask;
        cpudata->gfpu.xsh_xcomp_bv = 0;
 
-       /* Bluntly hide the host TSC. */
-       cpudata->tsc_offset = rdtsc();
+       /* Set guest TSC to zero, more or less. */
+       cpudata->tsc_offset = -cpu_counter();
 
        /* These MSRs are static. */
        cpudata->star = rdmsr(MSR_STAR);
diff -r 126d69463098 -r 1ace3b0bc3ad sys/dev/nvmm/x86/nvmm_x86_vmx.c
--- a/sys/dev/nvmm/x86/nvmm_x86_vmx.c   Fri Feb 15 08:54:01 2019 +0000
+++ b/sys/dev/nvmm/x86/nvmm_x86_vmx.c   Fri Feb 15 13:17:05 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm_x86_vmx.c,v 1.3 2019/02/14 14:30:20 maxv Exp $    */
+/*     $NetBSD: nvmm_x86_vmx.c,v 1.4 2019/02/15 13:17:05 maxv Exp $    */
 
 /*
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvmm_x86_vmx.c,v 1.3 2019/02/14 14:30:20 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvmm_x86_vmx.c,v 1.4 2019/02/15 13:17:05 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -46,6 +46,7 @@
 #include <x86/specialreg.h>
 #include <x86/pmap.h>
 #include <x86/dbregs.h>
+#include <x86/cpu_counter.h>
 #include <machine/cpuvar.h>
 
 #include <dev/nvmm/nvmm.h>
@@ -1370,6 +1371,12 @@
                }
                break;
        case NVMM_EXIT_MSR_WRMSR:
+               if (exit->u.msr.msr == MSR_TSC) {
+                       cpudata->tsc_offset = exit->u.msr.val - cpu_counter();
+                       vmx_vmwrite(VMCS_TSC_OFFSET, cpudata->tsc_offset +
+                           curcpu()->ci_data.cpu_cc_skew);
+                       goto handled;
+               }
                if (exit->u.msr.msr == MSR_CR_PAT) {
                        vmx_vmwrite(VMCS_GUEST_IA32_PAT, exit->u.msr.val);
                        goto handled;
@@ -2009,8 +2016,8 @@
        cpudata->gfpu.xsh_xstate_bv = vmx_xcr0_mask;
        cpudata->gfpu.xsh_xcomp_bv = 0;
 
-       /* Bluntly hide the host TSC. */
-       cpudata->tsc_offset = rdtsc();
+       /* Set guest TSC to zero, more or less. */
+       cpudata->tsc_offset = -cpu_counter();
 
        /* These MSRs are static. */
        cpudata->star = rdmsr(MSR_STAR);