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

From: Juergen Gross
Date: Fri Oct 07 2022 - 02:42:19 EST


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@xxxxxxxx>
---
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@xxxxxxxx>");
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