Author: neel
Date: Sat Sep 7 05:30:34 2013
New Revision: 255343
URL: http://svnweb.freebsd.org/changeset/base/255343
Log:
Allocate VPIDs by using the unit number allocator to keep do the bookkeeping.
Also deal with VPID exhaustion by allocating out of a reserved range as the
last resort.
Modified:
head/sys/amd64/vmm/intel/vmx.c
Modified: head/sys/amd64/vmm/intel/vmx.c
==============================================================================
--- head/sys/amd64/vmm/intel/vmx.c Sat Sep 7 03:33:36 2013
(r255342)
+++ head/sys/amd64/vmm/intel/vmx.c Sat Sep 7 05:30:34 2013
(r255343)
@@ -138,8 +138,6 @@ SYSCTL_ULONG(_hw_vmm_vmx, OID_AUTO, cr4_
SYSCTL_ULONG(_hw_vmm_vmx, OID_AUTO, cr4_zeros_mask, CTLFLAG_RD,
&cr4_zeros_mask, 0, NULL);
-static volatile u_int nextvpid;
-
static int vmx_no_patmsr;
static int vmx_initialized;
@@ -172,6 +170,11 @@ static int cap_monitor_trap;
/* statistics */
static VMM_STAT_INTEL(VMEXIT_HLT_IGNORED, "number of times hlt was ignored");
+static struct unrhdr *vpid_unr;
+static u_int vpid_alloc_failed;
+SYSCTL_UINT(_hw_vmm_vmx, OID_AUTO, vpid_alloc_failed, CTLFLAG_RD,
+ &vpid_alloc_failed, 0, NULL);
+
#ifdef KTR
static const char *
exit_reason_to_str(int reason)
@@ -382,6 +385,88 @@ vmx_fix_cr4(u_long cr4)
}
static void
+vpid_free(int vpid)
+{
+ if (vpid < 0 || vpid > 0xffff)
+ panic("vpid_free: invalid vpid %d", vpid);
+
+ /*
+ * VPIDs [0,VM_MAXCPU] are special and are not allocated from
+ * the unit number allocator.
+ */
+
+ if (vpid > VM_MAXCPU)
+ free_unr(vpid_unr, vpid);
+}
+
+static void
+vpid_alloc(uint16_t *vpid, int num)
+{
+ int i, x;
+
+ if (num <= 0 || num > VM_MAXCPU)
+ panic("invalid number of vpids requested: %d", num);
+
+ /*
+ * If the "enable vpid" execution control is not enabled then the
+ * VPID is required to be 0 for all vcpus.
+ */
+ if ((procbased_ctls2 & PROCBASED2_ENABLE_VPID) == 0) {
+ for (i = 0; i < num; i++)
+ vpid[i] = 0;
+ return;
+ }
+
+ /*
+ * Allocate a unique VPID for each vcpu from the unit number allocator.
+ */
+ for (i = 0; i < num; i++) {
+ x = alloc_unr(vpid_unr);
+ if (x == -1)
+ break;
+ else
+ vpid[i] = x;
+ }
+
+ if (i < num) {
+ atomic_add_int(&vpid_alloc_failed, 1);
+
+ /*
+ * If the unit number allocator does not have enough unique
+ * VPIDs then we need to allocate from the [1,VM_MAXCPU] range.
+ *
+ * These VPIDs are not be unique across VMs but this does not
+ * affect correctness because the combined mappings are also
+ * tagged with the EP4TA which is unique for each VM.
+ *
+ * It is still sub-optimal because the invvpid will invalidate
+ * combined mappings for a particular VPID across all EP4TAs.
+ */
+ while (i-- > 0)
+ vpid_free(vpid[i]);
+
+ for (i = 0; i < num; i++)
+ vpid[i] = i + 1;
+ }
+}
+
+static void
+vpid_init(void)
+{
+ /*
+ * VPID 0 is required when the "enable VPID" execution control is
+ * disabled.
+ *
+ * VPIDs [1,VM_MAXCPU] are used as the "overflow namespace" when the
+ * unit number allocator does not have sufficient unique VPIDs to
+ * satisfy the allocation.
+ *
+ * The remaining VPIDs are managed by the unit number allocator.
+ */
+ vpid_unr = new_unrhdr(VM_MAXCPU + 1, 0xffff, NULL);
+}
+
+static void
msr_save_area_init(struct msr_entry *g_area, int *g_count)
{
int cnt;
@@ -422,6 +507,11 @@ static int
vmx_cleanup(void)
{
+ if (vpid_unr != NULL) {
+ delete_unrhdr(vpid_unr);
+ vpid_unr = NULL;
+ }
+
smp_rendezvous(NULL, vmx_disable, NULL, NULL);
return (0);
@@ -607,6 +697,8 @@ vmx_init(void)
cr4_ones_mask = fixed0 & fixed1;
cr4_zeros_mask = ~fixed0 & ~fixed1;
+ vpid_init();
+
/* enable VMX operation */
smp_rendezvous(NULL, vmx_enable, NULL, NULL);
@@ -615,37 +707,6 @@ vmx_init(void)
return (0);
}
-/*
- * If this processor does not support VPIDs then simply return 0.
- *
- * Otherwise generate the next value of VPID to use. Any value is alright
- * as long as it is non-zero.
- *
- * We always execute in VMX non-root context with EPT enabled. Thus all
- * combined mappings are tagged with the (EP4TA, VPID, PCID) tuple. This
- * in turn means that multiple VMs can share the same VPID as long as
- * they have distinct EPT page tables.
- *
- * XXX
- * We should optimize this so that it returns VPIDs that are not in
- * use. Then we will not unnecessarily invalidate mappings in
- * vmx_set_pcpu_defaults() just because two or more vcpus happen to
- * use the same 'vpid'.
- */
-static uint16_t
-vmx_vpid(void)
-{
- uint16_t vpid = 0;
-
- if ((procbased_ctls2 & PROCBASED2_ENABLE_VPID) != 0) {
- do {
- vpid = atomic_fetchadd_int(&nextvpid, 1);
- } while (vpid == 0);
- }
-
- return (vpid);
-}
-
static int
vmx_setup_cr_shadow(int which, struct vmcs *vmcs, uint32_t initial)
{
@@ -681,7 +742,7 @@ vmx_setup_cr_shadow(int which, struct vm
static void *
vmx_vminit(struct vm *vm)
{
- uint16_t vpid;
+ uint16_t vpid[VM_MAXCPU];
int i, error, guest_msr_count;
struct vmx *vmx;
@@ -744,6 +805,8 @@ vmx_vminit(struct vm *vm)
if (!vmx_no_patmsr && guest_msr_rw(vmx, MSR_PAT))
panic("vmx_vminit: error setting guest pat msr access");
+ vpid_alloc(vpid, VM_MAXCPU);
+
for (i = 0; i < VM_MAXCPU; i++) {
vmx->vmcs[i].identifier = vmx_revision();
error = vmclear(&vmx->vmcs[i]);
@@ -752,8 +815,6 @@ vmx_vminit(struct vm *vm)
error, i);
}
- vpid = vmx_vpid();
-
error = vmcs_set_defaults(&vmx->vmcs[i],
(u_long)vmx_longjmp,
(u_long)&vmx->ctx[i],
@@ -763,7 +824,7 @@ vmx_vminit(struct vm *vm)
procbased_ctls2,
exit_ctls, entry_ctls,
vtophys(vmx->msr_bitmap),
- vpid);
+ vpid[i]);
if (error != 0)
panic("vmx_vminit: vmcs_set_defaults error %d", error);
@@ -772,7 +833,7 @@ vmx_vminit(struct vm *vm)
vmx->cap[i].proc_ctls = procbased_ctls;
vmx->state[i].lastcpu = -1;
- vmx->state[i].vpid = vpid;
+ vmx->state[i].vpid = vpid[i];
msr_save_area_init(vmx->guest_msrs[i], &guest_msr_count);
@@ -1580,9 +1641,12 @@ err_exit:
static void
vmx_vmcleanup(void *arg)
{
- int error;
+ int i, error;
struct vmx *vmx = arg;
+ for (i = 0; i < VM_MAXCPU; i++)
+ vpid_free(vmx->state[i].vpid);
+
/*
* XXXSMP we also need to clear the VMCS active on the other vcpus.
*/
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