linux-kernel - [PATCH v2 3/3] xen/virtio: enable grant based virtio on x86

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Message-Id: <20221007064143.10049-4-jgross@suse.com>
Date:   Fri,  7 Oct 2022 08:41:43 +0200
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        xen-devel@...ts.xenproject.org
Subject: [PATCH v2 3/3] xen/virtio: enable grant based virtio on x86

Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup
the correct DMA ops.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
V2:
- add missing PV check in xen_virtio_mem_acc() (Oleksandr Tyshchenko)
- add xen_virtio_restricted_mem_acc() stub (Oleksandr Tyshchenko)
---
 arch/x86/xen/enlighten_hvm.c |  2 +-
 arch/x86/xen/enlighten_pv.c  |  2 +-
 drivers/xen/grant-dma-ops.c  | 12 +++++++++++-
 include/xen/xen-ops.h        |  6 ++++++
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 1c1ac418484b..c1cd28e915a3 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -212,7 +212,7 @@ static void __init xen_hvm_guest_init(void)
 		return;
 
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
-		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
 
 	init_hvm_pv_info();
 
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 9b1a58dda935..45b24c1b646a 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -112,7 +112,7 @@ static void __init xen_pv_init_platform(void)
 {
 	/* PV guests can't operate virtio devices without grants. */
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO))
-		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
 
 	populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
 
diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index c703b77b33c9..63c3f0dac066 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -297,7 +297,7 @@ bool xen_is_grant_dma_device(struct device *dev)
 
 bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
-	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
+	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain())
 		return true;
 
 	return xen_is_grant_dma_device(dev->dev.parent);
@@ -372,6 +372,16 @@ void xen_grant_setup_dma_ops(struct device *dev)
 	dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n");
 }
 
+bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
+{
+	bool ret = xen_virtio_mem_acc(dev);
+
+	if (ret)
+		xen_grant_setup_dma_ops(dev->dev.parent);
+
+	return ret;
+}
+
 MODULE_DESCRIPTION("Xen grant DMA-mapping layer");
 MODULE_AUTHOR("Juergen Gross <jgross@...e.com>");
 MODULE_LICENSE("GPL");
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index dae0f350c678..a34f4271a2e9 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -219,6 +219,7 @@ static inline void xen_preemptible_hcall_end(void) { }
 void xen_grant_setup_dma_ops(struct device *dev);
 bool xen_is_grant_dma_device(struct device *dev);
 bool xen_virtio_mem_acc(struct virtio_device *dev);
+bool xen_virtio_restricted_mem_acc(struct virtio_device *dev);
 #else
 static inline void xen_grant_setup_dma_ops(struct device *dev)
 {
@@ -234,6 +235,11 @@ static inline bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
 	return false;
 }
+
+static inline bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
+{
+	return false;
+}
 #endif /* CONFIG_XEN_GRANT_DMA_OPS */
 
 #endif /* INCLUDE_XEN_OPS_H */
-- 
2.35.3