diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2017-10-06 17:48:54 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-10-10 12:53:00 +0200 |
| commit | a3b7424392924e778b608e30ee321f7b10cc94b8 (patch) | |
| tree | 91d209fb697122bffcffb9225a1b97a5b6036acf /arch/x86/hyperv | |
| parent | x86/unwind: Disable unwinder warnings on 32-bit (diff) | |
| download | linux-a3b7424392924e778b608e30ee321f7b10cc94b8.tar.xz linux-a3b7424392924e778b608e30ee321f7b10cc94b8.zip | |
x86/hyperv: Clear vCPU banks between calls to avoid flushing unneeded vCPUs
hv_flush_pcpu_ex structures are not cleared between calls for performance
reasons (they're variable size up to PAGE_SIZE each) but we must clear
hv_vp_set.bank_contents part of it to avoid flushing unneeded vCPUs. The
rest of the structure is formed correctly.
To do the clearing in an efficient way stash the maximum possible vCPU
number (this may differ from Linux CPU id).
Reported-by: Jork Loeser <Jork.Loeser@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: devel@linuxdriverproject.org
Link: http://lkml.kernel.org/r/20171006154854.18092-1-vkuznets@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/hyperv')
| -rw-r--r-- | arch/x86/hyperv/hv_init.c | 5 | ||||
| -rw-r--r-- | arch/x86/hyperv/mmu.c | 17 |
2 files changed, 17 insertions, 5 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 1a8eb550c40f..a5db63f728a2 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -85,6 +85,8 @@ EXPORT_SYMBOL_GPL(hyperv_cs); u32 *hv_vp_index; EXPORT_SYMBOL_GPL(hv_vp_index); +u32 hv_max_vp_index; + static int hv_cpu_init(unsigned int cpu) { u64 msr_vp_index; @@ -93,6 +95,9 @@ static int hv_cpu_init(unsigned int cpu) hv_vp_index[smp_processor_id()] = msr_vp_index; + if (msr_vp_index > hv_max_vp_index) + hv_max_vp_index = msr_vp_index; + return 0; } diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c index 39e7f6e50919..9502d04c0c95 100644 --- a/arch/x86/hyperv/mmu.c +++ b/arch/x86/hyperv/mmu.c @@ -76,6 +76,18 @@ static inline int cpumask_to_vp_set(struct hv_flush_pcpu_ex *flush, { int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1; + /* valid_bank_mask can represent up to 64 banks */ + if (hv_max_vp_index / 64 >= 64) + return 0; + + /* + * Clear all banks up to the maximum possible bank as hv_flush_pcpu_ex + * structs are not cleared between calls, we risk flushing unneeded + * vCPUs otherwise. + */ + for (vcpu_bank = 0; vcpu_bank <= hv_max_vp_index / 64; vcpu_bank++) + flush->hv_vp_set.bank_contents[vcpu_bank] = 0; + /* * Some banks may end up being empty but this is acceptable. */ @@ -83,11 +95,6 @@ static inline int cpumask_to_vp_set(struct hv_flush_pcpu_ex *flush, vcpu = hv_cpu_number_to_vp_number(cpu); vcpu_bank = vcpu / 64; vcpu_offset = vcpu % 64; - - /* valid_bank_mask can represent up to 64 banks */ - if (vcpu_bank >= 64) - return 0; - __set_bit(vcpu_offset, (unsigned long *) &flush->hv_vp_set.bank_contents[vcpu_bank]); if (vcpu_bank >= nr_bank) |