On Fri, 22 Dec 2017 22:22:08 +1100
Michael Ellerman [off-list ref] wrote:

Paul Mackerras [off-list ref] writes:
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On Fri, Dec 22, 2017 at 03:34:20PM +1100, Michael Ellerman wrote: =20

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Laurent Vivier [off-list ref] writes:
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On 12/12/2017 13:02, C=C3=A9dric Le Goater wrote: =20

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When restoring a pending interrupt, we are setting the Q bit to for=

ce

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a retrigger in xive_finish_unmask(). But we also need to force an E=

OI

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in this case to reach the same initial state : P=3D1, Q=3D0.
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This can be done by not setting 'old_p' for pending interrupts which
will inform xive_finish_unmask() that an EOI needs to be sent.
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Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: C=C3=A9dric Le Goater <clg@kaod.org>
---
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 Tested with a guest running iozone.
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 arch/powerpc/kvm/book3s_xive.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-) =20

We really need this patch to fix VM migration on POWER9.
When will it be merged? =20

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Paul is away, so I'll merge it via the powerpc tree.
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I'll mark it:
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  Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE =

interrupt controller")

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  Cc: stable@vger.kernel.org # v4.12+ =20

Thanks for doing that.

If you felt like merging Alexey's patch "KVM: PPC: Book3S PR: Fix WIMG
handling under pHyp" with my acked-by, that would be fine too.  The
commit message needs a little work - the reason for using HPTE_R_M is
not just because it seems to work, but because current POWER
processors require M set on mappings for normal pages, and pHyp
enforces that. =20

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OK. I saw this too late, but I'll pick that one up next week. If someone
sends me an updated change log I will merge all of their patches for
ever.
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Really ? Opportunity makes the thief, so here's my take :P

8<---------------------------------------------------------------------->8
KVM: PPC: Book3S: fix XIVE migration of pending interrupts

96df226 "KVM: PPC: Book3S PR: Preserve storage control bits" added WIMG
bits preserving but it missed 2 special cases:
- a magic page in kvmppc_mmu_book3s_64_xlate() and
- guest real mode in kvmppc_handle_pagefault().

For these ptes WIMG were 0 and pHyp failed on these causing a guest to
stop in the very beginning at NIP=3D0x100 (due to bd9166ffe
"KVM: PPC: Book3S PR: Exit KVM on failed mapping").

According to LoPAPR v1.1 14.5.4.1.2 H_ENTER:

 The hypervisor checks that the WIMG bits within the PTE are appropriate
 for the physical page number else H_Parameter return. (For System Memory
 pages WIMG=3D0010, or, 1110 if the SAO option is enabled, and for IO pages
 WIMG=3D01**.)

This hence initializes WIMG to non-zero value HPTE_R_M (0x10), as expected
by pHyp.

Fixes: 96df226 "KVM: PPC: Book3S PR: Preserve storage control bits"
Signed-off-by: Alexey Kardashevskiy <redacted>
8<---------------------------------------------------------------------->8

Cheers,

--
Greg

cheers
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