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[Qemu-devel] [PATCH 5/9] memory: let address_space_rw/ld*/st* run outsid
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 5/9] memory: let address_space_rw/ld*/st* run outside the BQL |
Date: |
Wed, 24 Jun 2015 18:25:06 +0200 |
From: Jan Kiszka <address@hidden>
The MMIO case is further broken up in two cases: if the caller does not
hold the BQL on invocation, the unlocked one takes or avoids BQL depending
on the locking strategy of the target memory region and its coalesced
MMIO handling. In this case, the caller should not hold _any_ lock
(a friendly suggestion which is disregarded by virtio-scsi-dataplane).
Signed-off-by: Jan Kiszka <address@hidden>
Cc: Frederic Konrad <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
exec.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 60 insertions(+), 9 deletions(-)
diff --git a/exec.c b/exec.c
index f2e6603..fd0401e 100644
--- a/exec.c
+++ b/exec.c
@@ -48,6 +48,7 @@
#endif
#include "exec/cpu-all.h"
#include "qemu/rcu_queue.h"
+#include "qemu/main-loop.h"
#include "exec/cputlb.h"
#include "translate-all.h"
@@ -2316,11 +2317,27 @@ static int memory_access_size(MemoryRegion *mr,
unsigned l, hwaddr addr)
return l;
}
-static void prepare_mmio_access(MemoryRegion *mr)
+static bool prepare_mmio_access(MemoryRegion *mr)
{
+ bool unlocked = !qemu_mutex_iothread_locked();
+ bool release_lock = false;
+
+ if (unlocked && mr->global_locking) {
+ qemu_mutex_lock_iothread();
+ unlocked = false;
+ release_lock = true;
+ }
if (mr->flush_coalesced_mmio) {
+ if (unlocked) {
+ qemu_mutex_lock_iothread();
+ }
qemu_flush_coalesced_mmio_buffer();
+ if (unlocked) {
+ qemu_mutex_unlock_iothread();
+ }
}
+
+ return release_lock;
}
MemTxResult address_space_rw(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
@@ -2332,6 +2349,7 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr
addr, MemTxAttrs attrs,
hwaddr addr1;
MemoryRegion *mr;
MemTxResult result = MEMTX_OK;
+ bool release_lock = false;
rcu_read_lock();
while (len > 0) {
@@ -2340,7 +2358,7 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr
addr, MemTxAttrs attrs,
if (is_write) {
if (!memory_access_is_direct(mr, is_write)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
l = memory_access_size(mr, l, addr1);
/* XXX: could force current_cpu to NULL to avoid
potential bugs */
@@ -2382,7 +2400,7 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr
addr, MemTxAttrs attrs,
} else {
if (!memory_access_is_direct(mr, is_write)) {
/* I/O case */
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
l = memory_access_size(mr, l, addr1);
switch (l) {
case 8:
@@ -2418,6 +2436,12 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr
addr, MemTxAttrs attrs,
memcpy(buf, ptr, l);
}
}
+
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ release_lock = false;
+ }
+
len -= l;
buf += l;
addr += l;
@@ -2744,11 +2768,12 @@ static inline uint32_t
address_space_ldl_internal(AddressSpace *as, hwaddr addr,
hwaddr l = 4;
hwaddr addr1;
MemTxResult r;
+ bool release_lock = false;
rcu_read_lock();
mr = address_space_translate(as, addr, &addr1, &l, false);
if (l < 4 || !memory_access_is_direct(mr, false)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
/* I/O case */
r = memory_region_dispatch_read(mr, addr1, &val, 4, attrs);
@@ -2782,6 +2807,9 @@ static inline uint32_t
address_space_ldl_internal(AddressSpace *as, hwaddr addr,
if (result) {
*result = r;
}
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
rcu_read_unlock();
return val;
}
@@ -2834,12 +2862,13 @@ static inline uint64_t
address_space_ldq_internal(AddressSpace *as, hwaddr addr,
hwaddr l = 8;
hwaddr addr1;
MemTxResult r;
+ bool release_lock = false;
rcu_read_lock();
mr = address_space_translate(as, addr, &addr1, &l,
false);
if (l < 8 || !memory_access_is_direct(mr, false)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
/* I/O case */
r = memory_region_dispatch_read(mr, addr1, &val, 8, attrs);
@@ -2873,6 +2902,9 @@ static inline uint64_t
address_space_ldq_internal(AddressSpace *as, hwaddr addr,
if (result) {
*result = r;
}
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
rcu_read_unlock();
return val;
}
@@ -2945,12 +2977,13 @@ static inline uint32_t
address_space_lduw_internal(AddressSpace *as,
hwaddr l = 2;
hwaddr addr1;
MemTxResult r;
+ bool release_lock = false;
rcu_read_lock();
mr = address_space_translate(as, addr, &addr1, &l,
false);
if (l < 2 || !memory_access_is_direct(mr, false)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
/* I/O case */
r = memory_region_dispatch_read(mr, addr1, &val, 2, attrs);
@@ -2984,6 +3017,9 @@ static inline uint32_t
address_space_lduw_internal(AddressSpace *as,
if (result) {
*result = r;
}
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
rcu_read_unlock();
return val;
}
@@ -3036,12 +3072,13 @@ void address_space_stl_notdirty(AddressSpace *as,
hwaddr addr, uint32_t val,
hwaddr addr1;
MemTxResult r;
uint8_t dirty_log_mask;
+ bool release_lock = false;
rcu_read_lock();
mr = address_space_translate(as, addr, &addr1, &l,
true);
if (l < 4 || !memory_access_is_direct(mr, true)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
r = memory_region_dispatch_write(mr, addr1, val, 4, attrs);
} else {
@@ -3057,6 +3094,9 @@ void address_space_stl_notdirty(AddressSpace *as, hwaddr
addr, uint32_t val,
if (result) {
*result = r;
}
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
rcu_read_unlock();
}
@@ -3077,12 +3117,13 @@ static inline void
address_space_stl_internal(AddressSpace *as,
hwaddr l = 4;
hwaddr addr1;
MemTxResult r;
+ bool release_lock = false;
rcu_read_lock();
mr = address_space_translate(as, addr, &addr1, &l,
true);
if (l < 4 || !memory_access_is_direct(mr, true)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
#if defined(TARGET_WORDS_BIGENDIAN)
if (endian == DEVICE_LITTLE_ENDIAN) {
@@ -3115,6 +3156,9 @@ static inline void
address_space_stl_internal(AddressSpace *as,
if (result) {
*result = r;
}
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
rcu_read_unlock();
}
@@ -3184,11 +3228,12 @@ static inline void
address_space_stw_internal(AddressSpace *as,
hwaddr l = 2;
hwaddr addr1;
MemTxResult r;
+ bool release_lock = false;
rcu_read_lock();
mr = address_space_translate(as, addr, &addr1, &l, true);
if (l < 2 || !memory_access_is_direct(mr, true)) {
- prepare_mmio_access(mr);
+ release_lock |= prepare_mmio_access(mr);
#if defined(TARGET_WORDS_BIGENDIAN)
if (endian == DEVICE_LITTLE_ENDIAN) {
@@ -3221,6 +3266,12 @@ static inline void
address_space_stw_internal(AddressSpace *as,
if (result) {
*result = r;
}
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
+ if (release_lock) {
+ qemu_mutex_unlock_iothread();
+ }
rcu_read_unlock();
}
--
1.8.3.1
- [Qemu-devel] [PATCH for-2.4 v2 0/9] KVM: Do I/O outside BQL whenever possible, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 3/9] memory: Add global-locking property to memory regions, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 4/9] exec: pull qemu_flush_coalesced_mmio_buffer() into address_space_rw/ld*/st*, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 1/9] main-loop: use qemu_mutex_lock_iothread consistently, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 2/9] main-loop: introduce qemu_mutex_iothread_locked, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 5/9] memory: let address_space_rw/ld*/st* run outside the BQL,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 7/9] kvm: Switch to unlocked PIO, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 8/9] acpi: mark PMTIMER as unlocked, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 9/9] kvm: Switch to unlocked MMIO, Paolo Bonzini, 2015/06/24
- [Qemu-devel] [PATCH 6/9] kvm: First step to push iothread lock out of inner run loop, Paolo Bonzini, 2015/06/24