linux-kernel - [PATCH RFC v2 16/18] dmaengine: idxd: add new wq state for mdev

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Message-ID: <159534744069.28840.5832146066812507209.stgit@djiang5-desk3.ch.intel.com>
Date:   Tue, 21 Jul 2020 09:04:00 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     vkoul@...nel.org, megha.dey@...el.com, maz@...nel.org,
        bhelgaas@...gle.com, rafael@...nel.org, gregkh@...uxfoundation.org,
        tglx@...utronix.de, hpa@...or.com, alex.williamson@...hat.com,
        jacob.jun.pan@...el.com, ashok.raj@...el.com, jgg@...lanox.com,
        yi.l.liu@...el.com, baolu.lu@...el.com, kevin.tian@...el.com,
        sanjay.k.kumar@...el.com, tony.luck@...el.com, jing.lin@...el.com,
        dan.j.williams@...el.com, kwankhede@...dia.com,
        eric.auger@...hat.com, parav@...lanox.com, jgg@...lanox.com,
        rafael@...nel.org, dave.hansen@...el.com, netanelg@...lanox.com,
        shahafs@...lanox.com, yan.y.zhao@...ux.intel.com,
        pbonzini@...hat.com, samuel.ortiz@...el.com, mona.hossain@...el.com
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-pci@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH RFC v2 16/18] dmaengine: idxd: add new wq state for mdev

When a dedicated wq is enabled as mdev, we must disable the wq on the
device in order to program the pasid to the wq. Introduce a wq state
IDXD_WQ_LOCKED that is software state only in order to prevent the user
from modifying the configuration while mdev wq is in this state. While
in this state, the wq is not in DISABLED state and will prevent any
modifications to the configuration. It is also not in the ENABLED state
and therefore prevents any actions allowed in the ENABLED state.

Signed-off-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Kevin Tian <kevin.tian@...el.com>
---
 drivers/dma/idxd/idxd.h  |    1 +
 drivers/dma/idxd/mdev.c  |    4 +++-
 drivers/dma/idxd/sysfs.c |    2 ++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 1f03019bb45d..cc0665335aee 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -60,6 +60,7 @@ struct idxd_group {
 enum idxd_wq_state {
 	IDXD_WQ_DISABLED = 0,
 	IDXD_WQ_ENABLED,
+	IDXD_WQ_LOCKED,
 };
 
 enum idxd_wq_flag {
diff --git a/drivers/dma/idxd/mdev.c b/drivers/dma/idxd/mdev.c
index 744adfdc06cd..e3c32f9566b5 100644
--- a/drivers/dma/idxd/mdev.c
+++ b/drivers/dma/idxd/mdev.c
@@ -69,8 +69,10 @@ static void idxd_vdcm_init(struct vdcm_idxd *vidxd)
 
 	vidxd_mmio_init(vidxd);
 
-	if (wq_dedicated(wq) && wq->state == IDXD_WQ_ENABLED)
+	if (wq_dedicated(wq) && wq->state == IDXD_WQ_ENABLED) {
 		idxd_wq_disable(wq, NULL);
+		wq->state = IDXD_WQ_LOCKED;
+	}
 }
 
 static void __idxd_vdcm_release(struct vdcm_idxd *vidxd)
diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
index d3b0a95b0d1d..6344cc719897 100644
--- a/drivers/dma/idxd/sysfs.c
+++ b/drivers/dma/idxd/sysfs.c
@@ -822,6 +822,8 @@ static ssize_t wq_state_show(struct device *dev,
 		return sprintf(buf, "disabled\n");
 	case IDXD_WQ_ENABLED:
 		return sprintf(buf, "enabled\n");
+	case IDXD_WQ_LOCKED:
+		return sprintf(buf, "locked\n");
 	}
 
 	return sprintf(buf, "unknown\n");