linux-kernel - [PATCH kernel v7 01/20] powerpc/ioda/npu: Call skiboot's hot reset hook when disabling NPU2

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Message-Id: <20181220082350.58113-2-aik@ozlabs.ru>
Date:   Thu, 20 Dec 2018 19:23:31 +1100
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     Alexey Kardashevskiy <aik@...abs.ru>,
        David Gibson <david@...son.dropbear.id.au>,
        kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
        Alistair Popple <alistair@...ple.id.au>,
        Reza Arbab <arbab@...ux.ibm.com>,
        Sam Bobroff <sbobroff@...ux.ibm.com>,
        Piotr Jaroszynski <pjaroszynski@...dia.com>,
        Leonardo Augusto Guimarães Garcia 
        <lagarcia@...ibm.com>, Jose Ricardo Ziviani <joserz@...ux.ibm.com>,
        Daniel Henrique Barboza <danielhb413@...il.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Paul Mackerras <paulus@...abs.org>,
        linux-kernel@...r.kernel.org, Christoph Hellwig <hch@...radead.org>
Subject: [PATCH kernel v7 01/20] powerpc/ioda/npu: Call skiboot's hot reset hook when disabling NPU2

The skiboot firmware has a hot reset handler which fences the NVIDIA V100
GPU RAM on Witherspoons and makes accesses no-op instead of throwing HMIs:
https://github.com/open-power/skiboot/commit/fca2b2b839a67

Now we are going to pass V100 via VFIO which most certainly involves
KVM guests which are often terminated without getting a chance to offline
GPU RAM so we end up with a running machine with misconfigured memory.
Accessing this memory produces hardware management interrupts (HMI)
which bring the host down.

To suppress HMIs, this wires up this hot reset hook to vfio_pci_disable()
via pci_disable_device() which switches NPU2 to a safe mode and prevents
HMIs.

Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Acked-by: Alistair Popple <alistair@...ple.id.au>
Reviewed-by: David Gibson <david@...son.dropbear.id.au>
---
Changes:
v2:
* updated the commit log
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 9ee7a30..29c6837 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3676,6 +3676,15 @@ static void pnv_pci_release_device(struct pci_dev *pdev)
 		pnv_ioda_release_pe(pe);
 }
 
+static void pnv_npu_disable_device(struct pci_dev *pdev)
+{
+	struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
+	struct eeh_pe *eehpe = edev ? edev->pe : NULL;
+
+	if (eehpe && eeh_ops && eeh_ops->reset)
+		eeh_ops->reset(eehpe, EEH_RESET_HOT);
+}
+
 static void pnv_pci_ioda_shutdown(struct pci_controller *hose)
 {
 	struct pnv_phb *phb = hose->private_data;
@@ -3720,6 +3729,7 @@ static const struct pci_controller_ops pnv_npu_ioda_controller_ops = {
 	.reset_secondary_bus	= pnv_pci_reset_secondary_bus,
 	.dma_set_mask		= pnv_npu_dma_set_mask,
 	.shutdown		= pnv_pci_ioda_shutdown,
+	.disable_device		= pnv_npu_disable_device,
 };
 
 static const struct pci_controller_ops pnv_npu_ocapi_ioda_controller_ops = {
-- 
2.17.1