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author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-24 09:18:48 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-24 09:18:48 -0800 |
commit | b24e2bdde4af656bb0679a101265ebb8f8735d3c (patch) | |
tree | 4a7bcc9bb7568136615a356dcc237c6f3e7c1cc1 | |
parent | 84257ce6b798a0eed0b4637694137be941903cf7 (diff) | |
parent | 5054daa285beaf706f051fbd395dc36c9f0f907f (diff) | |
download | op-kernel-dev-b24e2bdde4af656bb0679a101265ebb8f8735d3c.zip op-kernel-dev-b24e2bdde4af656bb0679a101265ebb8f8735d3c.tar.gz |
Merge tag 'stable/for-linus-4.0-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen bugfixes from David Vrabel:
"Xen regression and bug fixes for 4.0-rc1
- Fix two regressions introduced in 4.0-rc1 affecting PV/PVH guests
in certain configurations.
- Prevent pvscsi frontends bypassing backend checks.
- Allow privcmd hypercalls to be preempted even on kernel with
voluntary preemption. This fixes soft-lockups with long running
toolstack hypercalls (e.g., when creating/destroying large
domains)"
* tag 'stable/for-linus-4.0-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
x86/xen: Initialize cr4 shadow for 64-bit PV(H) guests
xen-scsiback: mark pvscsi frontend request consumed only after last read
x86/xen: allow privcmd hypercalls to be preempted
x86/xen: Make sure X2APIC_ENABLE bit of MSR_IA32_APICBASE is not set
-rw-r--r-- | arch/x86/kernel/entry_32.S | 3 | ||||
-rw-r--r-- | arch/x86/kernel/entry_64.S | 3 | ||||
-rw-r--r-- | arch/x86/xen/enlighten.c | 20 | ||||
-rw-r--r-- | drivers/xen/Makefile | 2 | ||||
-rw-r--r-- | drivers/xen/preempt.c | 44 | ||||
-rw-r--r-- | drivers/xen/privcmd.c | 2 | ||||
-rw-r--r-- | drivers/xen/xen-scsiback.c | 14 | ||||
-rw-r--r-- | include/xen/xen-ops.h | 26 |
8 files changed, 104 insertions, 10 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 000d419..31e2d5b 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -982,6 +982,9 @@ ENTRY(xen_hypervisor_callback) ENTRY(xen_do_upcall) 1: mov %esp, %eax call xen_evtchn_do_upcall +#ifndef CONFIG_PREEMPT + call xen_maybe_preempt_hcall +#endif jmp ret_from_intr CFI_ENDPROC ENDPROC(xen_hypervisor_callback) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index db13655..10074ad 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1208,6 +1208,9 @@ ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs) popq %rsp CFI_DEF_CFA_REGISTER rsp decl PER_CPU_VAR(irq_count) +#ifndef CONFIG_PREEMPT + call xen_maybe_preempt_hcall +#endif jmp error_exit CFI_ENDPROC END(xen_do_hypervisor_callback) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index bd8b845..5240f56 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1070,6 +1070,23 @@ static inline void xen_write_cr8(unsigned long val) BUG_ON(val); } #endif + +static u64 xen_read_msr_safe(unsigned int msr, int *err) +{ + u64 val; + + val = native_read_msr_safe(msr, err); + switch (msr) { + case MSR_IA32_APICBASE: +#ifdef CONFIG_X86_X2APIC + if (!(cpuid_ecx(1) & (1 << (X86_FEATURE_X2APIC & 31)))) +#endif + val &= ~X2APIC_ENABLE; + break; + } + return val; +} + static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) { int ret; @@ -1240,7 +1257,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = { .wbinvd = native_wbinvd, - .read_msr = native_read_msr_safe, + .read_msr = xen_read_msr_safe, .write_msr = xen_write_msr_safe, .read_tsc = native_read_tsc, @@ -1741,6 +1758,7 @@ asmlinkage __visible void __init xen_start_kernel(void) #ifdef CONFIG_X86_32 i386_start_kernel(); #else + cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */ x86_64_start_reservations((char *)__pa_symbol(&boot_params)); #endif } diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 2140398..2ccd359 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -2,7 +2,7 @@ ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),) obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o endif obj-$(CONFIG_X86) += fallback.o -obj-y += grant-table.o features.o balloon.o manage.o +obj-y += grant-table.o features.o balloon.o manage.o preempt.o obj-y += events/ obj-y += xenbus/ diff --git a/drivers/xen/preempt.c b/drivers/xen/preempt.c new file mode 100644 index 0000000..a1800c1 --- /dev/null +++ b/drivers/xen/preempt.c @@ -0,0 +1,44 @@ +/* + * Preemptible hypercalls + * + * Copyright (C) 2014 Citrix Systems R&D ltd. + * + * This source code is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + */ + +#include <linux/sched.h> +#include <xen/xen-ops.h> + +#ifndef CONFIG_PREEMPT + +/* + * Some hypercalls issued by the toolstack can take many 10s of + * seconds. Allow tasks running hypercalls via the privcmd driver to + * be voluntarily preempted even if full kernel preemption is + * disabled. + * + * Such preemptible hypercalls are bracketed by + * xen_preemptible_hcall_begin() and xen_preemptible_hcall_end() + * calls. + */ + +DEFINE_PER_CPU(bool, xen_in_preemptible_hcall); +EXPORT_SYMBOL_GPL(xen_in_preemptible_hcall); + +asmlinkage __visible void xen_maybe_preempt_hcall(void) +{ + if (unlikely(__this_cpu_read(xen_in_preemptible_hcall) + && should_resched())) { + /* + * Clear flag as we may be rescheduled on a different + * cpu. + */ + __this_cpu_write(xen_in_preemptible_hcall, false); + _cond_resched(); + __this_cpu_write(xen_in_preemptible_hcall, true); + } +} +#endif /* CONFIG_PREEMPT */ diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 569a13b..59ac71c 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -56,10 +56,12 @@ static long privcmd_ioctl_hypercall(void __user *udata) if (copy_from_user(&hypercall, udata, sizeof(hypercall))) return -EFAULT; + xen_preemptible_hcall_begin(); ret = privcmd_call(hypercall.op, hypercall.arg[0], hypercall.arg[1], hypercall.arg[2], hypercall.arg[3], hypercall.arg[4]); + xen_preemptible_hcall_end(); return ret; } diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index 61653a0..9faca6a 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -709,12 +709,11 @@ static int prepare_pending_reqs(struct vscsibk_info *info, static int scsiback_do_cmd_fn(struct vscsibk_info *info) { struct vscsiif_back_ring *ring = &info->ring; - struct vscsiif_request *ring_req; + struct vscsiif_request ring_req; struct vscsibk_pend *pending_req; RING_IDX rc, rp; int err, more_to_do; uint32_t result; - uint8_t act; rc = ring->req_cons; rp = ring->sring->req_prod; @@ -735,11 +734,10 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) if (!pending_req) return 1; - ring_req = RING_GET_REQUEST(ring, rc); + ring_req = *RING_GET_REQUEST(ring, rc); ring->req_cons = ++rc; - act = ring_req->act; - err = prepare_pending_reqs(info, ring_req, pending_req); + err = prepare_pending_reqs(info, &ring_req, pending_req); if (err) { switch (err) { case -ENODEV: @@ -755,9 +753,9 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) return 1; } - switch (act) { + switch (ring_req.act) { case VSCSIIF_ACT_SCSI_CDB: - if (scsiback_gnttab_data_map(ring_req, pending_req)) { + if (scsiback_gnttab_data_map(&ring_req, pending_req)) { scsiback_fast_flush_area(pending_req); scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24, 0, pending_req); @@ -768,7 +766,7 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) break; case VSCSIIF_ACT_SCSI_ABORT: scsiback_device_action(pending_req, TMR_ABORT_TASK, - ring_req->ref_rqid); + ring_req.ref_rqid); break; case VSCSIIF_ACT_SCSI_RESET: scsiback_device_action(pending_req, TMR_LUN_RESET, 0); diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h index 7491ee5..8333821 100644 --- a/include/xen/xen-ops.h +++ b/include/xen/xen-ops.h @@ -46,4 +46,30 @@ static inline efi_system_table_t __init *xen_efi_probe(void) } #endif +#ifdef CONFIG_PREEMPT + +static inline void xen_preemptible_hcall_begin(void) +{ +} + +static inline void xen_preemptible_hcall_end(void) +{ +} + +#else + +DECLARE_PER_CPU(bool, xen_in_preemptible_hcall); + +static inline void xen_preemptible_hcall_begin(void) +{ + __this_cpu_write(xen_in_preemptible_hcall, true); +} + +static inline void xen_preemptible_hcall_end(void) +{ + __this_cpu_write(xen_in_preemptible_hcall, false); +} + +#endif /* CONFIG_PREEMPT */ + #endif /* INCLUDE_XEN_OPS_H */ |