From a12c52d18cf67392ea5ec12b590ce5e5061bee54 Mon Sep 17 00:00:00 2001 From: Igor Druzhinin Date: Thu, 5 Mar 2020 11:36:29 +0100 Subject: [PATCH] x86/shim: suspend and resume platform time correctly MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Similarly to S3, platform time needs to be saved on guest suspend and restored on resume respectively. This should account for expected jumps in PV clock counter value after resume. time_suspend/resume() are safe to use in PVH setting as is since any existing operations with PIT/HPET that they do would simply be ignored if PIT/HPET is not present. Additionally, add resume callback for Xen PV clocksource to avoid its breakage on migration. Signed-off-by: Igor Druzhinin Reviewed-by: Roger Pau Monné master commit: a7a3ecd82e289a9a2ecc1d3b5128580e0b577cc7 master date: 2020-02-14 18:01:52 +0000 --- xen/arch/x86/pv/shim.c | 7 ++++++- xen/arch/x86/time.c | 12 +++++++++--- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c index d4146fe234..353538447e 100644 --- a/xen/arch/x86/pv/shim.c +++ b/xen/arch/x86/pv/shim.c @@ -279,9 +279,13 @@ int pv_shim_shutdown(uint8_t reason) if ( v != current ) vcpu_pause_by_systemcontroller(v); + /* Prepare timekeeping code to suspend.*/ + time_suspend(); + rc = xen_hypercall_shutdown(SHUTDOWN_suspend); if ( rc ) { + time_resume(); for_each_vcpu ( d, v ) if ( v != current ) vcpu_unpause_by_systemcontroller(v); @@ -289,8 +293,9 @@ int pv_shim_shutdown(uint8_t reason) return rc; } - /* Resume the shim itself first. */ + /* Resume the shim itself and timekeeping first. */ hypervisor_resume(); + time_resume(); /* * ATM there's nothing Xen can do if the console/store pfn changes, diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c index 373b10b6dc..fd4c8bc4f0 100644 --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -562,6 +562,7 @@ static struct platform_timesource __initdata plt_tsc = * * Xen clock source is a variant of TSC source. */ +static uint64_t xen_timer_last; static uint64_t xen_timer_cpu_frequency(void) { @@ -607,7 +608,6 @@ static uint64_t read_xen_timer(void) uint32_t version; uint64_t ret; uint64_t last; - static uint64_t last_value; do { version = info->version & ~1; @@ -623,20 +623,26 @@ static uint64_t read_xen_timer(void) /* Maintain a monotonic global value */ do { - last = read_atomic(&last_value); + last = read_atomic(&xen_timer_last); if ( ret < last ) return last; - } while ( unlikely(cmpxchg(&last_value, last, ret) != last) ); + } while ( unlikely(cmpxchg(&xen_timer_last, last, ret) != last) ); return ret; } +static void resume_xen_timer(struct platform_timesource *pts) +{ + write_atomic(&xen_timer_last, 0); +} + static struct platform_timesource __initdata plt_xen_timer = { .id = "xen", .name = "XEN PV CLOCK", .read_counter = read_xen_timer, .init = init_xen_timer, + .resume = resume_xen_timer, .counter_bits = 63, }; #endif -- 2.30.2