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authorVitaly Kuznetsov <vkuznets@redhat.com>2017-10-05 13:39:24 +0200
committerIngo Molnar <mingo@kernel.org>2017-10-10 12:54:56 +0200
commit60d73a7c96601434dfdb56d5b9167ff3b850d8d7 (patch)
tree12248a7085e4fac767e9e20236d7a91fd47e40cf /arch
parentx86/hyperv: Clear vCPU banks between calls to avoid flushing unneeded vCPUs (diff)
downloadlinux-60d73a7c96601434dfdb56d5b9167ff3b850d8d7.tar.xz
linux-60d73a7c96601434dfdb56d5b9167ff3b850d8d7.zip
x86/hyperv: Don't use percpu areas for pcpu_flush/pcpu_flush_ex structures
hv_do_hypercall() does virt_to_phys() translation and with some configs (CONFIG_SLAB) this doesn't work for percpu areas, we pass wrong memory to hypervisor and get #GP. We could use working slow_virt_to_phys() instead but doing so kills the performance. Move pcpu_flush/pcpu_flush_ex structures out of percpu areas and allocate memory on first call. The additional level of indirection gives us a small performance penalty, in future we may consider introducing hypercall functions which avoid virt_to_phys() conversion and cache physical addresses of pcpu_flush/pcpu_flush_ex structures somewhere. Reported-by: Simon Xiao <sixiao@microsoft.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Dexuan Cui <decui@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jork Loeser <Jork.Loeser@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/20171005113924.28021-1-vkuznets@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/hyperv/mmu.c34
1 files changed, 28 insertions, 6 deletions
diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 9502d04c0c95..f21cebbb5f6c 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -36,9 +36,9 @@ struct hv_flush_pcpu_ex {
/* Each gva in gva_list encodes up to 4096 pages to flush */
#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE)
-static struct hv_flush_pcpu __percpu *pcpu_flush;
+static struct hv_flush_pcpu __percpu **pcpu_flush;
-static struct hv_flush_pcpu_ex __percpu *pcpu_flush_ex;
+static struct hv_flush_pcpu_ex __percpu **pcpu_flush_ex;
/*
* Fills in gva_list starting from offset. Returns the number of items added.
@@ -109,6 +109,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
const struct flush_tlb_info *info)
{
int cpu, vcpu, gva_n, max_gvas;
+ struct hv_flush_pcpu **flush_pcpu;
struct hv_flush_pcpu *flush;
u64 status = U64_MAX;
unsigned long flags;
@@ -123,7 +124,17 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
local_irq_save(flags);
- flush = this_cpu_ptr(pcpu_flush);
+ flush_pcpu = this_cpu_ptr(pcpu_flush);
+
+ if (unlikely(!*flush_pcpu))
+ *flush_pcpu = page_address(alloc_page(GFP_ATOMIC));
+
+ flush = *flush_pcpu;
+
+ if (unlikely(!flush)) {
+ local_irq_restore(flags);
+ goto do_native;
+ }
if (info->mm) {
flush->address_space = virt_to_phys(info->mm->pgd);
@@ -180,6 +191,7 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
const struct flush_tlb_info *info)
{
int nr_bank = 0, max_gvas, gva_n;
+ struct hv_flush_pcpu_ex **flush_pcpu;
struct hv_flush_pcpu_ex *flush;
u64 status = U64_MAX;
unsigned long flags;
@@ -194,7 +206,17 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
local_irq_save(flags);
- flush = this_cpu_ptr(pcpu_flush_ex);
+ flush_pcpu = this_cpu_ptr(pcpu_flush_ex);
+
+ if (unlikely(!*flush_pcpu))
+ *flush_pcpu = page_address(alloc_page(GFP_ATOMIC));
+
+ flush = *flush_pcpu;
+
+ if (unlikely(!flush)) {
+ local_irq_restore(flags);
+ goto do_native;
+ }
if (info->mm) {
flush->address_space = virt_to_phys(info->mm->pgd);
@@ -273,7 +295,7 @@ void hyper_alloc_mmu(void)
return;
if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
- pcpu_flush = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
+ pcpu_flush = alloc_percpu(struct hv_flush_pcpu *);
else
- pcpu_flush_ex = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
+ pcpu_flush_ex = alloc_percpu(struct hv_flush_pcpu_ex *);
}