* [PATCH v3 1/2] xen/arm: add support for vm_assist hypercall
2016-06-17 5:26 [PATCH v3 0/2] Support consistent reads of mapped vcpu_runstate_info Juergen Gross
@ 2016-06-17 5:26 ` Juergen Gross
2016-06-17 5:26 ` [PATCH v3 2/2] xen: add update indicator to vcpu_runstate_info Juergen Gross
1 sibling, 0 replies; 5+ messages in thread
From: Juergen Gross @ 2016-06-17 5:26 UTC (permalink / raw)
To: xen-devel
Cc: Juergen Gross, sstabellini, wei.liu2, George.Dunlap,
andrew.cooper3, ian.jackson, tim, julien.grall, jbeulich
Up to now the vm_assist hypercall hasn't been supported on ARM, as
there are only x86 specific features to switch. Add support of
vm_assist on ARM for future use.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
---
V2: readded the #ifdef's as requested by Jan Beulich
---
xen/arch/arm/traps.c | 1 +
xen/include/asm-arm/config.h | 2 ++
2 files changed, 3 insertions(+)
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index aa3e3c2..44926ca 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1282,6 +1282,7 @@ static arm_hypercall_t arm_hypercall_table[] = {
HYPERCALL(multicall, 2),
HYPERCALL(platform_op, 1),
HYPERCALL_ARM(vcpu_op, 3),
+ HYPERCALL(vm_assist, 2),
};
#ifndef NDEBUG
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index 2d11b62..563f49b 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -199,6 +199,8 @@ extern unsigned long frametable_virt_end;
#define watchdog_disable() ((void)0)
#define watchdog_enable() ((void)0)
+#define VM_ASSIST_VALID (0)
+
#endif /* __ARM_CONFIG_H__ */
/*
* Local variables:
--
2.6.6
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^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v3 2/2] xen: add update indicator to vcpu_runstate_info
2016-06-17 5:26 [PATCH v3 0/2] Support consistent reads of mapped vcpu_runstate_info Juergen Gross
2016-06-17 5:26 ` [PATCH v3 1/2] xen/arm: add support for vm_assist hypercall Juergen Gross
@ 2016-06-17 5:26 ` Juergen Gross
2016-06-17 8:03 ` Jan Beulich
2016-06-20 17:36 ` Julien Grall
1 sibling, 2 replies; 5+ messages in thread
From: Juergen Gross @ 2016-06-17 5:26 UTC (permalink / raw)
To: xen-devel
Cc: Juergen Gross, sstabellini, wei.liu2, George.Dunlap,
andrew.cooper3, ian.jackson, tim, julien.grall, jbeulich
In order to support reading another vcpu's mapped vcpu_runstate_info
an indicator for an occurring update of the runstate information is
needed.
Add the possibility to activate setting this indicator in the highest
bit of state_entry_time via a vm_assist hypercall. When activated the
update indicator will be set before the runstate information is
modified in guest memory and it will be reset after modification is
done. As state_entry_time is guaranteed to be different after each
update the guest can detect any update (either in progress or while
reading the runstate data) by comparing state_entry_time before and
after reading runstate data: in case the values differ or the update
indicator was set the data might be inconsistent and should be reread.
Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3: simplify update_runstate_area() address calculation as requested
by Jan Beulich
V2: smp_wmb() instead of wmb() as requested by Andrew Cooper
use sizeof() as requested by Jan Beulich
eliminate new variable update_flag as requested by Jan Beulich
---
xen/arch/arm/domain.c | 20 ++++++++++++++++++++
xen/arch/x86/domain.c | 21 +++++++++++++++++++++
xen/include/asm-arm/config.h | 2 +-
xen/include/asm-x86/config.h | 1 +
xen/include/public/vcpu.h | 6 ++++++
xen/include/public/xen.h | 7 +++++++
6 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 1365b4a..2ace1bc 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -239,10 +239,30 @@ static void ctxt_switch_to(struct vcpu *n)
/* Update per-VCPU guest runstate shared memory area (if registered). */
static void update_runstate_area(struct vcpu *v)
{
+ void __user *guest_handle = NULL;
+
if ( guest_handle_is_null(runstate_guest(v)) )
return;
+ if ( VM_ASSIST(v->domain, runstate_update_flag) )
+ {
+ guest_handle = &v->runstate_guest.p->state_entry_time + 1;
+ guest_handle--;
+ v->runstate.state_entry_time |= XEN_RUNSTATE_UPDATE;
+ __raw_copy_to_guest(guest_handle,
+ (void *)(&v->runstate.state_entry_time + 1) - 1, 1);
+ smp_wmb();
+ }
+
__copy_to_guest(runstate_guest(v), &v->runstate, 1);
+
+ if ( guest_handle )
+ {
+ v->runstate.state_entry_time &= ~XEN_RUNSTATE_UPDATE;
+ smp_wmb();
+ __raw_copy_to_guest(guest_handle,
+ (void *)(&v->runstate.state_entry_time + 1) - 1, 1);
+ }
}
static void schedule_tail(struct vcpu *prev)
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 989bc74..3ba7ed1 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1926,12 +1926,25 @@ bool_t update_runstate_area(struct vcpu *v)
{
bool_t rc;
smap_check_policy_t smap_policy;
+ void __user *guest_handle = NULL;
if ( guest_handle_is_null(runstate_guest(v)) )
return 1;
smap_policy = smap_policy_change(v, SMAP_CHECK_ENABLED);
+ if ( VM_ASSIST(v->domain, runstate_update_flag) )
+ {
+ guest_handle = has_32bit_shinfo(v->domain)
+ ? &v->runstate_guest.compat.p->state_entry_time + 1
+ : &v->runstate_guest.native.p->state_entry_time + 1;
+ guest_handle--;
+ v->runstate.state_entry_time |= XEN_RUNSTATE_UPDATE;
+ __raw_copy_to_guest(guest_handle,
+ (void *)(&v->runstate.state_entry_time + 1) - 1, 1);
+ smp_wmb();
+ }
+
if ( has_32bit_shinfo(v->domain) )
{
struct compat_vcpu_runstate_info info;
@@ -1944,6 +1957,14 @@ bool_t update_runstate_area(struct vcpu *v)
rc = __copy_to_guest(runstate_guest(v), &v->runstate, 1) !=
sizeof(v->runstate);
+ if ( guest_handle )
+ {
+ v->runstate.state_entry_time &= ~XEN_RUNSTATE_UPDATE;
+ smp_wmb();
+ __raw_copy_to_guest(guest_handle,
+ (void *)(&v->runstate.state_entry_time + 1) - 1, 1);
+ }
+
smap_policy_change(v, smap_policy);
return rc;
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index 563f49b..ce3edc2 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -199,7 +199,7 @@ extern unsigned long frametable_virt_end;
#define watchdog_disable() ((void)0)
#define watchdog_enable() ((void)0)
-#define VM_ASSIST_VALID (0)
+#define VM_ASSIST_VALID (1UL << VMASST_TYPE_runstate_update_flag)
#endif /* __ARM_CONFIG_H__ */
/*
diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index c10129d..6fd84e7 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -332,6 +332,7 @@ extern unsigned long xen_phys_start;
(1UL << VMASST_TYPE_writable_pagetables) | \
(1UL << VMASST_TYPE_pae_extended_cr3) | \
(1UL << VMASST_TYPE_architectural_iopl) | \
+ (1UL << VMASST_TYPE_runstate_update_flag)| \
(1UL << VMASST_TYPE_m2p_strict))
#define VM_ASSIST_VALID NATIVE_VM_ASSIST_VALID
#define COMPAT_VM_ASSIST_VALID (NATIVE_VM_ASSIST_VALID & \
diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
index 692b87a..2aa230d 100644
--- a/xen/include/public/vcpu.h
+++ b/xen/include/public/vcpu.h
@@ -84,6 +84,12 @@ struct vcpu_runstate_info {
/* When was current state entered (system time, ns)? */
uint64_t state_entry_time;
/*
+ * Update indicator set in state_entry_time:
+ * When activated via VMASST_TYPE_runstate_update_flag, set during
+ * updates in guest memory mapped copy of vcpu_runstate_info.
+ */
+#define XEN_RUNSTATE_UPDATE (1ULL << 63)
+ /*
* Time spent in each RUNSTATE_* (ns). The sum of these times is
* guaranteed not to drift from system time.
*/
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 37bbb22..b9e5e0f 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -510,6 +510,13 @@ DEFINE_XEN_GUEST_HANDLE(mmuext_op_t);
#define VMASST_TYPE_architectural_iopl 4
/*
+ * All guests: activate update indicator in vcpu_runstate_info
+ * Enable setting the XEN_RUNSTATE_UPDATE flag in guest memory mapped
+ * vcpu_runstate_info during updates of the runstate information.
+ */
+#define VMASST_TYPE_runstate_update_flag 5
+
+/*
* x86/64 guests: strictly hide M2P from user mode.
* This allows the guest to control respective hypervisor behavior:
* - when not set, L4 tables get created with the respective slot blank,
--
2.6.6
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^ permalink raw reply related [flat|nested] 5+ messages in thread