[src/trunk]: src/sys/dev/nvmm Optimize: keep a per-VCPU buffer for the state, ...

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

details:   https://anonhg.NetBSD.org/src/rev/cd3c87cbfddc
branches:  trunk
changeset: 447844:cd3c87cbfddc
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sat Jan 26 15:25:51 2019 +0000

description:
Optimize: keep a per-VCPU buffer for the state, and copy in and out
directly on it. The VCPUs are protected by mutexes, so nothing to worry
about.

This saves two kmem_allocs in {get,set}state.

diffstat:

 sys/dev/nvmm/nvmm.c          |  30 ++++++++++--------------------
 sys/dev/nvmm/nvmm_internal.h |   5 ++++-
 2 files changed, 14 insertions(+), 21 deletions(-)

diffs (122 lines):

diff -r 3b5eb7a0f72d -r cd3c87cbfddc sys/dev/nvmm/nvmm.c
--- a/sys/dev/nvmm/nvmm.c       Sat Jan 26 15:22:54 2019 +0000
+++ b/sys/dev/nvmm/nvmm.c       Sat Jan 26 15:25:51 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm.c,v 1.5 2019/01/06 16:10:51 maxv Exp $    */
+/*     $NetBSD: nvmm.c,v 1.6 2019/01/26 15:25:51 maxv Exp $    */
 
 /*
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvmm.c,v 1.5 2019/01/06 16:10:51 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvmm.c,v 1.6 2019/01/26 15:25:51 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -142,6 +142,7 @@
 
                vcpu->present = true;
                vcpu->cpuid = i;
+               vcpu->state = kmem_zalloc(nvmm_impl->state_size, KM_SLEEP);
                *ret = vcpu;
                return 0;
        }
@@ -154,6 +155,7 @@
 {
        KASSERT(mutex_owned(&vcpu->lock));
        vcpu->present = false;
+       kmem_free(vcpu->state, nvmm_impl->state_size);
        vcpu->hcpu_last = -1;
 }
 
@@ -404,33 +406,27 @@
 {
        struct nvmm_machine *mach;
        struct nvmm_cpu *vcpu;
-       void *data;
        int error;
 
-       data = kmem_alloc(nvmm_impl->state_size, KM_SLEEP);
-
        error = nvmm_machine_get(args->machid, &mach, false);
-       if (error) {
-               kmem_free(data, nvmm_impl->state_size);
+       if (error)
                return error;
-       }
 
        error = nvmm_vcpu_get(mach, args->cpuid, &vcpu);
        if (error)
                goto out;
 
-       error = copyin(args->state, data, nvmm_impl->state_size);
+       error = copyin(args->state, vcpu->state, nvmm_impl->state_size);
        if (error) {
                nvmm_vcpu_put(vcpu);
                goto out;
        }
 
-       (*nvmm_impl->vcpu_setstate)(vcpu, data, args->flags);
+       (*nvmm_impl->vcpu_setstate)(vcpu, vcpu->state, args->flags);
        nvmm_vcpu_put(vcpu);
 
 out:
        nvmm_machine_put(mach);
-       kmem_free(data, nvmm_impl->state_size);
        return error;
 }
 
@@ -439,28 +435,22 @@
 {
        struct nvmm_machine *mach;
        struct nvmm_cpu *vcpu;
-       void *data;
        int error;
 
-       data = kmem_alloc(nvmm_impl->state_size, KM_SLEEP);
-
        error = nvmm_machine_get(args->machid, &mach, false);
-       if (error) {
-               kmem_free(data, nvmm_impl->state_size);
+       if (error)
                return error;
-       }
 
        error = nvmm_vcpu_get(mach, args->cpuid, &vcpu);
        if (error)
                goto out;
 
-       (*nvmm_impl->vcpu_getstate)(vcpu, data, args->flags);
+       (*nvmm_impl->vcpu_getstate)(vcpu, vcpu->state, args->flags);
        nvmm_vcpu_put(vcpu);
-       error = copyout(data, args->state, nvmm_impl->state_size);
+       error = copyout(vcpu->state, args->state, nvmm_impl->state_size);
 
 out:
        nvmm_machine_put(mach);
-       kmem_free(data, nvmm_impl->state_size);
        return error;
 }
 
diff -r 3b5eb7a0f72d -r cd3c87cbfddc sys/dev/nvmm/nvmm_internal.h
--- a/sys/dev/nvmm/nvmm_internal.h      Sat Jan 26 15:22:54 2019 +0000
+++ b/sys/dev/nvmm/nvmm_internal.h      Sat Jan 26 15:25:51 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm_internal.h,v 1.2 2018/12/15 13:39:43 maxv Exp $   */
+/*     $NetBSD: nvmm_internal.h,v 1.3 2019/01/26 15:25:51 maxv Exp $   */
 
 /*
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -43,6 +43,9 @@
        nvmm_cpuid_t cpuid;
        kmutex_t lock;
 
+       /* State buffer. */
+       void *state;
+
        /* Last host CPU on which the VCPU ran. */
        int hcpu_last;