a89d75605e
on Xen 576001df-x86-time-use-local-stamp-in-TSC-calibration-fast-path.patch 5769106e-x86-generate-assembler-equates-for-synthesized.patch 57a1e603-x86-time-adjust-local-system-time-initialization.patch 57a1e64c-x86-time-introduce-and-use-rdtsc_ordered.patch 57a2f6ac-x86-time-calibrate-TSC-against-platform-timer.patch - bsc#991934 - xen hypervisor crash in csched_acct 57973099-have-schedulers-revise-initial-placement.patch 579730e6-remove-buggy-initial-placement-algorithm.patch - bsc#988675 - VUL-0: CVE-2016-6258: xen: x86: Privilege escalation in PV guests (XSA-182) 57976073-x86-remove-unsafe-bits-from-mod_lN_entry-fastpath.patch - bsc#988676 - VUL-0: CVE-2016-6259: xen: x86: Missing SMAP whitelisting in 32-bit exception / event delivery (XSA-183) 57976078-x86-avoid-SMAP-violation-in-compat_create_bounce_frame.patch - Upstream patches from Jan 57a30261-x86-support-newer-Intel-CPU-models.patch - bsc#985503 - vif-route broken vif-route.patch OBS-URL: https://build.opensuse.org/package/show/Virtualization/xen?expand=0&rev=445
124 lines
3.6 KiB
Diff
124 lines
3.6 KiB
Diff
References: bsc#970135
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# Commit bb49fd3092a84ce151f5528794c0e612eeb4961a
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# Date 2016-08-03 14:39:31 +0200
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# Author Jan Beulich <jbeulich@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86/time: adjust local system time initialization
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Using the bare return value from read_platform_stime() is not suitable
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when local_time_calibration() is going to use its fast path: Divergence
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of several dozen microseconds between NOW() return values on different
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CPUs results when platform and local time don't stay in close sync.
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Latch local and platform time on the CPU initiating AP bringup, such
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that the AP can use these values to seed its stime_local_stamp with as
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little of an error as possible. The boot CPU, otoh, can simply
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calculate the correct initial value (other CPUs could do so too with
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even greater accuracy than the approach being introduced, but that can
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work only if all CPUs' TSCs start ticking at the same time, which
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generally can't be assumed to be the case on multi-socket systems).
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This slightly defers init_percpu_time() (moved ahead by commit
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dd2658f966 ["x86/time: initialise time earlier during
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start_secondary()"]) in order to reduce as much as possible the gap
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between populating the stamps and consuming them.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Tested-by: Dario Faggioli <dario.faggioli@citrix.com>
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Tested-by: Joao Martins <joao.m.martins@oracle.com>
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Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
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--- a/xen/arch/x86/smpboot.c
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+++ b/xen/arch/x86/smpboot.c
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@@ -328,12 +328,12 @@ void start_secondary(void *unused)
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percpu_traps_init();
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- init_percpu_time();
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-
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cpu_init();
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smp_callin();
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+ init_percpu_time();
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+
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setup_secondary_APIC_clock();
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/*
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@@ -996,6 +996,8 @@ int __cpu_up(unsigned int cpu)
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if ( (ret = do_boot_cpu(apicid, cpu)) != 0 )
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return ret;
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+ time_latch_stamps();
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+
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set_cpu_state(CPU_STATE_ONLINE);
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while ( !cpu_online(cpu) )
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{
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--- a/xen/arch/x86/time.c
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+++ b/xen/arch/x86/time.c
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@@ -1328,21 +1328,52 @@ static void time_calibration(void *unuse
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&r, 1);
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}
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+static struct {
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+ s_time_t local_stime, master_stime;
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+} ap_bringup_ref;
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+
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+void time_latch_stamps(void)
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+{
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+ unsigned long flags;
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+ u64 tsc;
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+
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+ local_irq_save(flags);
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+ ap_bringup_ref.master_stime = read_platform_stime();
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+ tsc = rdtsc();
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+ local_irq_restore(flags);
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+
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+ ap_bringup_ref.local_stime = get_s_time_fixed(tsc);
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+}
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+
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void init_percpu_time(void)
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{
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struct cpu_time *t = &this_cpu(cpu_time);
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unsigned long flags;
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+ u64 tsc;
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s_time_t now;
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/* Initial estimate for TSC rate. */
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t->tsc_scale = per_cpu(cpu_time, 0).tsc_scale;
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local_irq_save(flags);
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- t->local_tsc_stamp = rdtsc();
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now = read_platform_stime();
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+ tsc = rdtsc();
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local_irq_restore(flags);
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t->stime_master_stamp = now;
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+ /*
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+ * To avoid a discontinuity (TSC and platform clock can't be expected
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+ * to be in perfect sync), initialization here needs to match up with
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+ * local_time_calibration()'s decision whether to use its fast path.
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+ */
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+ if ( boot_cpu_has(X86_FEATURE_CONSTANT_TSC) )
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+ {
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+ if ( system_state < SYS_STATE_smp_boot )
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+ now = get_s_time_fixed(tsc);
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+ else
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+ now += ap_bringup_ref.local_stime - ap_bringup_ref.master_stime;
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+ }
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+ t->local_tsc_stamp = tsc;
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t->stime_local_stamp = now;
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}
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--- a/xen/include/asm-x86/time.h
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+++ b/xen/include/asm-x86/time.h
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@@ -40,6 +40,7 @@ int time_suspend(void);
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int time_resume(void);
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void init_percpu_time(void);
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+void time_latch_stamps(void);
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struct ioreq;
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int hwdom_pit_access(struct ioreq *ioreq);
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