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authorNicholas Piggin <npiggin@gmail.com>2023-06-29 12:07:13 +1000
committerDaniel Henrique Barboza <danielhb413@gmail.com>2023-07-07 04:18:26 -0300
commit2ad2e113deb5663e69a05dd6922cbfc6d7ea34d3 (patch)
treed0feab9444b294d4702f5fc34601e319a3f855ed /hw
parenta5ff7875a9e50180c354471f931f863a26283ce1 (diff)
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hw/ppc: Fix clock update drift
The clock update logic reads the clock twice to compute the new clock value, with a value derived from the later time subtracted from a value derived from the earlier time. The delta causes time to be lost. This can ultimately result in time becoming unsynchronized between CPUs and that can cause OS lockups, timeouts, watchdogs, etc. This can be seen running a KVM guest (that causes lots of TB updates) on a powernv SMP machine. Fix this by reading the clock once. Cc: qemu-stable@nongnu.org Fixes: dbdd25065e90 ("Implement time-base start/stop helpers.") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Cédric Le Goater <clg@kaod.org> Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com> Message-ID: <20230629020713.327745-1-npiggin@gmail.com> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Diffstat (limited to 'hw')
-rw-r--r--hw/ppc/ppc.c33
1 files changed, 17 insertions, 16 deletions
diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index 0fc82bb..0e0a3d9 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -535,23 +535,24 @@ static inline void cpu_ppc_store_tb(ppc_tb_t *tb_env, uint64_t vmclk,
void cpu_ppc_store_tbl (CPUPPCState *env, uint32_t value)
{
ppc_tb_t *tb_env = env->tb_env;
+ int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
uint64_t tb;
- tb = cpu_ppc_get_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), tb_env->tb_offset);
+ tb = cpu_ppc_get_tb(tb_env, clock, tb_env->tb_offset);
tb &= 0xFFFFFFFF00000000ULL;
- cpu_ppc_store_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- &tb_env->tb_offset, tb | (uint64_t)value);
+ cpu_ppc_store_tb(tb_env, clock, &tb_env->tb_offset, tb | (uint64_t)value);
}
static inline void _cpu_ppc_store_tbu(CPUPPCState *env, uint32_t value)
{
ppc_tb_t *tb_env = env->tb_env;
+ int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
uint64_t tb;
- tb = cpu_ppc_get_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), tb_env->tb_offset);
+ tb = cpu_ppc_get_tb(tb_env, clock, tb_env->tb_offset);
tb &= 0x00000000FFFFFFFFULL;
- cpu_ppc_store_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- &tb_env->tb_offset, ((uint64_t)value << 32) | tb);
+ cpu_ppc_store_tb(tb_env, clock, &tb_env->tb_offset,
+ ((uint64_t)value << 32) | tb);
}
void cpu_ppc_store_tbu (CPUPPCState *env, uint32_t value)
@@ -584,23 +585,24 @@ uint32_t cpu_ppc_load_atbu (CPUPPCState *env)
void cpu_ppc_store_atbl (CPUPPCState *env, uint32_t value)
{
ppc_tb_t *tb_env = env->tb_env;
+ int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
uint64_t tb;
- tb = cpu_ppc_get_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), tb_env->atb_offset);
+ tb = cpu_ppc_get_tb(tb_env, clock, tb_env->atb_offset);
tb &= 0xFFFFFFFF00000000ULL;
- cpu_ppc_store_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- &tb_env->atb_offset, tb | (uint64_t)value);
+ cpu_ppc_store_tb(tb_env, clock, &tb_env->atb_offset, tb | (uint64_t)value);
}
void cpu_ppc_store_atbu (CPUPPCState *env, uint32_t value)
{
ppc_tb_t *tb_env = env->tb_env;
+ int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
uint64_t tb;
- tb = cpu_ppc_get_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), tb_env->atb_offset);
+ tb = cpu_ppc_get_tb(tb_env, clock, tb_env->atb_offset);
tb &= 0x00000000FFFFFFFFULL;
- cpu_ppc_store_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- &tb_env->atb_offset, ((uint64_t)value << 32) | tb);
+ cpu_ppc_store_tb(tb_env, clock, &tb_env->atb_offset,
+ ((uint64_t)value << 32) | tb);
}
uint64_t cpu_ppc_load_vtb(CPUPPCState *env)
@@ -622,14 +624,13 @@ void cpu_ppc_store_vtb(CPUPPCState *env, uint64_t value)
void cpu_ppc_store_tbu40(CPUPPCState *env, uint64_t value)
{
ppc_tb_t *tb_env = env->tb_env;
+ int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
uint64_t tb;
- tb = cpu_ppc_get_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- tb_env->tb_offset);
+ tb = cpu_ppc_get_tb(tb_env, clock, tb_env->tb_offset);
tb &= 0xFFFFFFUL;
tb |= (value & ~0xFFFFFFUL);
- cpu_ppc_store_tb(tb_env, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- &tb_env->tb_offset, tb);
+ cpu_ppc_store_tb(tb_env, clock, &tb_env->tb_offset, tb);
}
static void cpu_ppc_tb_stop (CPUPPCState *env)