From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 5/5] x86/monitor: Capture Xen's intent to use monitor at boot time
Date: Thu, 18 Jan 2018 01:05:28 -0700 [thread overview]
Message-ID: <5A606358020000780019FB6A@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1515782244-6412-6-git-send-email-andrew.cooper3@citrix.com>
>>> On 12.01.18 at 19:37, <andrew.cooper3@citrix.com> wrote:
> @@ -312,6 +313,12 @@ static void generic_identify(struct cpuinfo_x86 *c)
> if ( cpu_has(c, X86_FEATURE_CLFLUSH) )
> c->x86_clflush_size = ((ebx >> 8) & 0xff) * 8;
>
> + /* Xen only uses MONITOR if INTERRUPT_BREAK is available. */
> + if ( cpu_has(c, X86_FEATURE_MONITOR) &&
> + ((cpuid_ecx(CPUID_MWAIT_LEAF) & CPUID_MWAIT_MIN_FEATURES) ==
> + CPUID_MWAIT_MIN_FEATURES) )
> + set_bit(X86_FEATURE_XEN_MONITOR, c->x86_capability);
Leaving aside that this could/should be __set_bit(), I think we
shouldn't do anything like this for synthetic feature bits and at
the same time ...
> @@ -104,6 +100,7 @@
> #define cpu_has_arch_perfmon boot_cpu_has(X86_FEATURE_ARCH_PERFMON)
> #define cpu_has_cpuid_faulting boot_cpu_has(X86_FEATURE_CPUID_FAULTING)
> #define cpu_has_aperfmperf boot_cpu_has(X86_FEATURE_APERFMPERF)
> +#define cpu_has_xen_monitor boot_cpu_has(X86_FEATURE_XEN_MONITOR)
... test for them like this. Either we're certain all CPUs are identical,
in which case the above should be setup_force_cpu_cap(), or each
CPU should really inspect its own feature flag before using the
feature. I'd got the former route for now, and with that change
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Jan
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prev parent reply other threads:[~2018-01-18 8:05 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 18:37 [PATCH 0/5] x86: Misc improvements from KAISER-prep work Andrew Cooper
2018-01-12 18:37 ` [PATCH 1/5] x86/idt: Factor out enabling and disabling of ISTs Andrew Cooper
2018-01-12 20:12 ` Doug Goldstein
2018-01-17 14:43 ` Wei Liu
2018-01-18 7:43 ` Jan Beulich
2018-01-12 18:37 ` [PATCH 2/5] x86/pv: Rename invalidate_shadow_ldt() to pv_destroy_ldt() Andrew Cooper
2018-01-12 20:15 ` Doug Goldstein
2018-01-17 14:43 ` Wei Liu
2018-01-18 7:45 ` Jan Beulich
2018-01-12 18:37 ` [PATCH 3/5] x86/pv: Break handle_ldt_mapping_fault() out of handle_gdt_ldt_mapping_fault() Andrew Cooper
2018-01-12 20:22 ` Doug Goldstein
2018-01-18 7:48 ` Jan Beulich
2018-01-12 18:37 ` [PATCH 4/5] x86/pv: Drop support for paging out the LDT Andrew Cooper
2018-01-12 21:53 ` Doug Goldstein
2018-01-18 7:59 ` Jan Beulich
2018-01-18 10:38 ` George Dunlap
2018-01-18 10:57 ` Jan Beulich
2018-01-18 10:57 ` Andrew Cooper
2018-01-18 11:00 ` Andrew Cooper
2018-01-18 11:37 ` Jan Beulich
2018-01-12 18:37 ` [PATCH 5/5] x86/monitor: Capture Xen's intent to use monitor at boot time Andrew Cooper
2018-01-18 8:05 ` Jan Beulich [this message]
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