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| author | Paul Mackerras <paulus@samba.org> | 2012-02-03 00:54:17 +0000 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2012-04-08 14:01:20 +0300 |
| commit | f0888f70151c7f53de2b45ee20ff1905837943e8 (patch) | |
| tree | 80b7e133e681a2b4e4255a8fa747711da4c59211 /arch/powerpc/kernel | |
| parent | f6127716c346c73ab1513edee53231800188c5ba (diff) | |
| download | kernel_goldelico_gta04-f0888f70151c7f53de2b45ee20ff1905837943e8.zip kernel_goldelico_gta04-f0888f70151c7f53de2b45ee20ff1905837943e8.tar.gz kernel_goldelico_gta04-f0888f70151c7f53de2b45ee20ff1905837943e8.tar.bz2 | |
KVM: PPC: Book3S HV: Make secondary threads more robust against stray IPIs
Currently on POWER7, if we are running the guest on a core and we don't
need all the hardware threads, we do nothing to ensure that the unused
threads aren't executing in the kernel (other than checking that they
are offline). We just assume they're napping and we don't do anything
to stop them trying to enter the kernel while the guest is running.
This means that a stray IPI can wake up the hardware thread and it will
then try to enter the kernel, but since the core is in guest context,
it will execute code from the guest in hypervisor mode once it turns the
MMU on, which tends to lead to crashes or hangs in the host.
This fixes the problem by adding two new one-byte flags in the
kvmppc_host_state structure in the PACA which are used to interlock
between the primary thread and the unused secondary threads when entering
the guest. With these flags, the primary thread can ensure that the
unused secondaries are not already in kernel mode (i.e. handling a stray
IPI) and then indicate that they should not try to enter the kernel
if they do get woken for any reason. Instead they will go into KVM code,
find that there is no vcpu to run, acknowledge and clear the IPI and go
back to nap mode.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/asm-offsets.c | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 12 | ||||
| -rw-r--r-- | arch/powerpc/kernel/idle_power7.S | 7 |
3 files changed, 16 insertions, 5 deletions
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index bbede58..2abcf7d 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -540,6 +540,8 @@ int main(void) HSTATE_FIELD(HSTATE_IN_GUEST, in_guest); HSTATE_FIELD(HSTATE_RESTORE_HID5, restore_hid5); HSTATE_FIELD(HSTATE_NAPPING, napping); + HSTATE_FIELD(HSTATE_HWTHREAD_REQ, hwthread_req); + HSTATE_FIELD(HSTATE_HWTHREAD_STATE, hwthread_state); #ifdef CONFIG_KVM_BOOK3S_64_HV HSTATE_FIELD(HSTATE_KVM_VCPU, kvm_vcpu); diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index cb705fd..8829b10 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -63,11 +63,13 @@ BEGIN_FTR_SECTION GET_PACA(r13) #ifdef CONFIG_KVM_BOOK3S_64_HV - lbz r0,PACAPROCSTART(r13) - cmpwi r0,0x80 - bne 1f - li r0,1 - stb r0,PACAPROCSTART(r13) + li r0,KVM_HWTHREAD_IN_KERNEL + stb r0,HSTATE_HWTHREAD_STATE(r13) + /* Order setting hwthread_state vs. testing hwthread_req */ + sync + lbz r0,HSTATE_HWTHREAD_REQ(r13) + cmpwi r0,0 + beq 1f b kvm_start_guest 1: #endif diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S index 0cdc9a3..7140d83 100644 --- a/arch/powerpc/kernel/idle_power7.S +++ b/arch/powerpc/kernel/idle_power7.S @@ -16,6 +16,7 @@ #include <asm/asm-offsets.h> #include <asm/ppc-opcode.h> #include <asm/hw_irq.h> +#include <asm/kvm_book3s_asm.h> #undef DEBUG @@ -81,6 +82,12 @@ _GLOBAL(power7_idle) std r9,_MSR(r1) std r1,PACAR1(r13) +#ifdef CONFIG_KVM_BOOK3S_64_HV + /* Tell KVM we're napping */ + li r4,KVM_HWTHREAD_IN_NAP + stb r4,HSTATE_HWTHREAD_STATE(r13) +#endif + /* Magic NAP mode enter sequence */ std r0,0(r1) ptesync |