Re: [PATCH] powerpc/kvm/booke: Fix build break due to stack frame size warning
On 11.12.2013, at 00:11, Scott Wood wrote:
> On Tue, 2013-12-10 at 03:05 +0100, Alexander Graf wrote:
>> On 09.12.2013, at 22:18, Scott Wood wrote:
>>
>>> On Mon, 2013-11-25 at 04:26 -0600, Bharat Bhushan wrote:
> -Original Message-
> From: Wood Scott-B07421
> Sent: Saturday, November 23, 2013 3:22 AM
> To: Alexander Graf
> Cc: kvm-ppc@vger.kernel.org; k...@vger.kernel.org; Wood Scott-B07421;
> Bhushan
> Bharat-R65777
> Subject: [PATCH] powerpc/kvm/booke: Fix build break due to stack frame
> size
> warning
>
> Commit ce11e48b7fdd256ec68b932a89b397a790566031 ("KVM: PPC: E500: Add
> userspace debug stub support") added "struct thread_struct" to the
> stack of kvmppc_vcpu_run(). thread_struct is 1152 bytes on my build,
> compared to 48 bytes for the recently-introduced "struct debug_reg".
> Use the latter instead.
>
> This fixes the following error:
>
> cc1: warnings being treated as errors
> arch/powerpc/kvm/booke.c: In function 'kvmppc_vcpu_run':
> arch/powerpc/kvm/booke.c:760:1: error: the frame size of 1424 bytes is
> larger
> than 1024 bytes
> make[2]: *** [arch/powerpc/kvm/booke.o] Error 1
> make[1]: *** [arch/powerpc/kvm] Error 2
> make[1]: *** Waiting for unfinished jobs
>
> Signed-off-by: Scott Wood
> Cc: Bharat Bhushan
> ---
> Build tested only. Bharat, please test.
Tested with qemu debug stub; It works fine
-Bharat
>>>
>>> Alex, are you going to take this through your tree?
>>
>> Sure. Do you want this for 3.13 or 3.14? Since I don't see the breakage
>> with my compilers I'd queue it for 3.14, but whatever works for you
>> works for me.
>
> 3.13 please. All I need to do to trigger the build break is enable KVM
> with corenet64_smp_defconfig with GCC 4.5.
Thanks, applied to the for-3.13 branch.
Alex
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Re: [PATCH] powerpc/kvm/booke: Fix build break due to stack frame size warning
On 11.12.2013, at 00:11, Scott Wood wrote:
> On Tue, 2013-12-10 at 03:05 +0100, Alexander Graf wrote:
>> On 09.12.2013, at 22:18, Scott Wood wrote:
>>
>>> On Mon, 2013-11-25 at 04:26 -0600, Bharat Bhushan wrote:
> -Original Message-
> From: Wood Scott-B07421
> Sent: Saturday, November 23, 2013 3:22 AM
> To: Alexander Graf
> Cc: kvm-ppc@vger.kernel.org; k...@vger.kernel.org; Wood Scott-B07421;
> Bhushan
> Bharat-R65777
> Subject: [PATCH] powerpc/kvm/booke: Fix build break due to stack frame
> size
> warning
>
> Commit ce11e48b7fdd256ec68b932a89b397a790566031 ("KVM: PPC: E500: Add
> userspace debug stub support") added "struct thread_struct" to the
> stack of kvmppc_vcpu_run(). thread_struct is 1152 bytes on my build,
> compared to 48 bytes for the recently-introduced "struct debug_reg".
> Use the latter instead.
>
> This fixes the following error:
>
> cc1: warnings being treated as errors
> arch/powerpc/kvm/booke.c: In function 'kvmppc_vcpu_run':
> arch/powerpc/kvm/booke.c:760:1: error: the frame size of 1424 bytes is
> larger
> than 1024 bytes
> make[2]: *** [arch/powerpc/kvm/booke.o] Error 1
> make[1]: *** [arch/powerpc/kvm] Error 2
> make[1]: *** Waiting for unfinished jobs
>
> Signed-off-by: Scott Wood
> Cc: Bharat Bhushan
> ---
> Build tested only. Bharat, please test.
Tested with qemu debug stub; It works fine
-Bharat
>>>
>>> Alex, are you going to take this through your tree?
>>
>> Sure. Do you want this for 3.13 or 3.14? Since I don't see the breakage
>> with my compilers I'd queue it for 3.14, but whatever works for you
>> works for me.
>
> 3.13 please. All I need to do to trigger the build break is enable KVM
> with corenet64_smp_defconfig with GCC 4.5.
Thanks, applied to the for-3.13 branch.
Alex
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Re: [PATCH] powerpc/kvm/booke: Fix build break due to stack frame size warning
On Tue, 2013-12-10 at 03:05 +0100, Alexander Graf wrote:
> On 09.12.2013, at 22:18, Scott Wood wrote:
>
> > On Mon, 2013-11-25 at 04:26 -0600, Bharat Bhushan wrote:
> >>
> >>> -Original Message-
> >>> From: Wood Scott-B07421
> >>> Sent: Saturday, November 23, 2013 3:22 AM
> >>> To: Alexander Graf
> >>> Cc: kvm-ppc@vger.kernel.org; k...@vger.kernel.org; Wood Scott-B07421;
> >>> Bhushan
> >>> Bharat-R65777
> >>> Subject: [PATCH] powerpc/kvm/booke: Fix build break due to stack frame
> >>> size
> >>> warning
> >>>
> >>> Commit ce11e48b7fdd256ec68b932a89b397a790566031 ("KVM: PPC: E500: Add
> >>> userspace debug stub support") added "struct thread_struct" to the
> >>> stack of kvmppc_vcpu_run(). thread_struct is 1152 bytes on my build,
> >>> compared to 48 bytes for the recently-introduced "struct debug_reg".
> >>> Use the latter instead.
> >>>
> >>> This fixes the following error:
> >>>
> >>> cc1: warnings being treated as errors
> >>> arch/powerpc/kvm/booke.c: In function 'kvmppc_vcpu_run':
> >>> arch/powerpc/kvm/booke.c:760:1: error: the frame size of 1424 bytes is
> >>> larger
> >>> than 1024 bytes
> >>> make[2]: *** [arch/powerpc/kvm/booke.o] Error 1
> >>> make[1]: *** [arch/powerpc/kvm] Error 2
> >>> make[1]: *** Waiting for unfinished jobs
> >>>
> >>> Signed-off-by: Scott Wood
> >>> Cc: Bharat Bhushan
> >>> ---
> >>> Build tested only. Bharat, please test.
> >>
> >> Tested with qemu debug stub; It works fine
> >>
> >> -Bharat
> >
> > Alex, are you going to take this through your tree?
>
> Sure. Do you want this for 3.13 or 3.14? Since I don't see the breakage
> with my compilers I'd queue it for 3.14, but whatever works for you
> works for me.
3.13 please. All I need to do to trigger the build break is enable KVM
with corenet64_smp_defconfig with GCC 4.5.
Oddly, I don't see it with newer GCCs (4.7.3 or 4.8.0). It looks like
it may be a bug in the stack frame warning in those newer versions.
This is the code from 4.8.0:
0e8c <.kvmppc_vcpu_run>:
.kvmppc_vcpu_run():
/home/scott/fsl/git/linux/upstream/arch/powerpc/kvm/booke.c:682
e8c: 7c 08 02 a6 mflrr0
e90: fb 41 ff d0 std r26,-48(r1)
e94: 7c 7a 1b 78 mr r26,r3
e98: fb a1 ff e8 std r29,-24(r1)
e9c: fb c1 ff f0 std r30,-16(r1)
ea0: 7c 9e 23 78 mr r30,r4
ea4: fb e1 ff f8 std r31,-8(r1)
ea8: f8 01 00 10 std r0,16(r1)
eac: fb 21 ff c8 std r25,-56(r1)
eb0: fb 61 ff d8 std r27,-40(r1)
eb4: fb 81 ff e0 std r28,-32(r1)
eb8: f8 21 fe 41 stdur1,-448(r1)
/home/scott/fsl/git/linux/upstream/arch/powerpc/kvm/booke.c:690
ebc: 89 44 08 a9 lbz r10,2217(r4)
/home/scott/fsl/git/linux/upstream/arch/powerpc/kvm/booke.c:682
ec0: 7c 3f 0b 78 mr r31,r1
ec4: e9 21 00 00 ld r9,0(r1)
/home/scott/fsl/git/linux/upstream/arch/powerpc/kvm/booke.c:690
ec8: 2f 8a 00 00 cmpwi cr7,r10,0
/home/scott/fsl/git/linux/upstream/arch/powerpc/kvm/booke.c:682
ecc: f9 21 fb 41 stdur9,-1216(r1)
ed0: 3b a1 00 af addir29,r1,175
ed4: 7b bd 06 64 rldicr r29,r29,0,57
The instruction at 0xecc expands the stack by 1216 bytes, on top of the
already allocated stack frame of 448 bytes. I'm not sure why it's
creating a secondary stack frame in this odd way.
GCC 4.5, which produces the warning, does this instead:
0eb8 <.kvmppc_vcpu_run>:
kvmppc_vcpu_run():
/home/scott/fsl/git/linux/upstream/arch/powerpc/kvm/booke.c:682
eb8: 7c 08 02 a6 mflrr0
ebc: fb 61 ff d8 std r27,-40(r1)
ec0: 7c 7b 1b 78 mr r27,r3
ec4: fb e1 ff f8 std r31,-8(r1)
ec8: 7c 9f 23 78 mr r31,r4
ecc: f8 01 00 10 std r0,16(r1)
ed0: fb 41 ff d0 std r26,-48(r1)
ed4: fb 81 ff e0 std r28,-32(r1)
ed8: fb a1 ff e8 std r29,-24(r1)
edc: f8 21 f9 d1 stdur1,-1584(r1)
-Scott
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Re: [PATCH] KVM: PPC: Use schedule instead of cond_resched
On Tue, 2013-12-10 at 23:48 +0100, Peter Zijlstra wrote: > > Yeah, I went on holidays and the patch just sat there. I'll prod Ingo > into merging it. Thanks ! Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: PPC: Use schedule instead of cond_resched
On Wed, Dec 11, 2013 at 07:52:51AM +1100, Benjamin Herrenschmidt wrote: > On Tue, 2013-12-10 at 15:40 +0100, Alexander Graf wrote: > > On 10.12.2013, at 15:21, Aneesh Kumar K.V > > wrote: > > > > > From: "Aneesh Kumar K.V" > > > > > > We already checked need_resched. So we can call schedule directly > > > > > > Signed-off-by: Aneesh Kumar K.V > > > > The real fix for the issue you're seeing is > > > > https://lkml.org/lkml/2013/11/28/241 > > > > And is still not upstream Peter ? Yeah, I went on holidays and the patch just sat there. I'll prod Ingo into merging it. -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: PPC: Use schedule instead of cond_resched
On Tue, 2013-12-10 at 15:40 +0100, Alexander Graf wrote: > On 10.12.2013, at 15:21, Aneesh Kumar K.V > wrote: > > > From: "Aneesh Kumar K.V" > > > > We already checked need_resched. So we can call schedule directly > > > > Signed-off-by: Aneesh Kumar K.V > > The real fix for the issue you're seeing is > > https://lkml.org/lkml/2013/11/28/241 > And is still not upstream Peter ? Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: PPC: Use schedule instead of cond_resched
On 10.12.2013, at 17:08, Aneesh Kumar K.V wrote: > Alexander Graf writes: > >> On 10.12.2013, at 15:21, Aneesh Kumar K.V >> wrote: >> >>> From: "Aneesh Kumar K.V" >>> >>> We already checked need_resched. So we can call schedule directly >>> >>> Signed-off-by: Aneesh Kumar K.V >> >> The real fix for the issue you're seeing is >> >> https://lkml.org/lkml/2013/11/28/241 > > True, I mentioned that in the thread > > https://lkml.org/lkml/2013/12/9/64 > > But do we need to do cond_resched after we checked for need_resched() ? This is really just copying the logic from kvm_resched() from virt/kvm/kvm_main.c. And I'd prefer not to diverge from that. I do agree that there's a good chance we don't need it, as it seems to predate preempt notifiers: https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=3fca03653010b8c5fa63b99fc94c78cbfb433d00 But this is a discussion that should occur on the non-ppc specific code first :). Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: PPC: Use schedule instead of cond_resched
Alexander Graf writes: > On 10.12.2013, at 15:21, Aneesh Kumar K.V > wrote: > >> From: "Aneesh Kumar K.V" >> >> We already checked need_resched. So we can call schedule directly >> >> Signed-off-by: Aneesh Kumar K.V > > The real fix for the issue you're seeing is > > https://lkml.org/lkml/2013/11/28/241 True, I mentioned that in the thread https://lkml.org/lkml/2013/12/9/64 But do we need to do cond_resched after we checked for need_resched() ? -aneesh -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: PPC: Use schedule instead of cond_resched
On 10.12.2013, at 15:21, Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > We already checked need_resched. So we can call schedule directly > > Signed-off-by: Aneesh Kumar K.V The real fix for the issue you're seeing is https://lkml.org/lkml/2013/11/28/241 Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] KVM: PPC: Use schedule instead of cond_resched
From: "Aneesh Kumar K.V"
We already checked need_resched. So we can call schedule directly
Signed-off-by: Aneesh Kumar K.V
---
NOTE: This patch also work around a regression upstream w.r.t PR KVM
BUG: soft lockup - CPU#0 stuck for 23s! [qemu-system-ppc:4394]
Modules linked in:
CPU: 0 PID: 4394 Comm: qemu-system-ppc Not tainted 3.13.0-rc3+ #98
task: c001d0788400 ti: c001dca0 task.ti: c001dca0
NIP: c082dd80 LR: c0081ae0 CTR: c0062ba0
REGS: c001dca02f70 TRAP: 0901 Not tainted (3.13.0-rc3+)
MSR: 80009032 CR: 24822024 XER:
CFAR: c0081adc SOFTE: 1
GPR00: c0081ae0 c001dca031f0 c0d67ab0 0001
GPR04: 7102 0001 0189a0d786b7 018c
GPR08: 0001 c0da
GPR12: 0c00 cfef
NIP [c082dd80] ._cond_resched+0x0/0x40
LR [c0081ae0] .kvmppc_prepare_to_enter+0x2a0/0x2e0
Call Trace:
[c001dca031f0] [c0081ae0] .kvmppc_prepare_to_enter+0x2a0/0x2e0
(unreliable)
[c001dca03290] [c008f2cc] .kvmppc_handle_exit_pr+0xec/0xa40
[c001dca03340] [c00918c4] kvm_start_lightweight+0xac/0xbc
[c001dca03510] [c008efe0] .kvmppc_vcpu_run_pr+0x130/0x2a0
[c001dca039e0] [c00855bc] .kvmppc_vcpu_run+0x2c/0x40
[c001dca03a50] [c0082c94] .kvm_arch_vcpu_ioctl_run+0x54/0x1b0
[c001dca03ae0] [c007d5f8] .kvm_vcpu_ioctl+0x478/0x740
[c001dca03ca0] [c0218864] .do_vfs_ioctl+0x4a4/0x760
[c001dca03d80] [c0218b78] .SyS_ioctl+0x58/0xb0
[c001dca03e30] [c0009e58] syscall_exit+0x0/0x98
Instruction dump:
e92d0260 e94911c0 812a0004 5529f07e 5529103e 912a0004 38210080 e8010010
ebc1fff0 ebe1fff8 7c0803a6 4e800020 <7c0802a6> 3860 f8010010 f821ff91
arch/powerpc/kvm/powerpc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index e4d511c8b38b..6a49b23a3276 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -74,7 +74,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
while (true) {
if (need_resched()) {
local_irq_enable();
- cond_resched();
+ schedule();
local_irq_disable();
continue;
}
--
1.8.3.2
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