[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH] xen: don't require virtio with grants for non-PV guests
Commit fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings") introduced a new requirement for using virtio devices: the backend now needs to support the VIRTIO_F_ACCESS_PLATFORM feature. This is an undue requirement for non-PV guests, as those can be operated with existing backends without any problem, as long as those backends are running in dom0. Per default allow virtio devices without grant support for non-PV guests. The setting can be overridden by using the new "xen_virtio_grant" command line parameter. Add a new config item to always force use of grants for virtio. Fixes: fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings") Signed-off-by: Juergen Gross <jgross@xxxxxxxx> --- .../admin-guide/kernel-parameters.txt | 6 +++++ drivers/xen/Kconfig | 9 ++++++++ drivers/xen/grant-dma-ops.c | 22 +++++++++++++++++++ include/xen/xen.h | 12 +++++----- 4 files changed, 42 insertions(+), 7 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 8090130b544b..7960480c6fe4 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6695,6 +6695,12 @@ improve timer resolution at the expense of processing more timer interrupts. + xen_virtio_grant= [XEN] + Control whether virtio devices are required to use + grants when running as a Xen guest. The default is + "yes" for PV guests or when the kernel has been built + with CONFIG_XEN_VIRTIO_FORCE_GRANT set. + xen.balloon_boot_timeout= [XEN] The time (in seconds) to wait before giving up to boot in case initial ballooning fails to free enough memory. diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index bfd5f4f706bc..a65bd92121a5 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -355,4 +355,13 @@ config XEN_VIRTIO If in doubt, say n. +config XEN_VIRTIO_FORCE_GRANT + bool "Require Xen virtio support to use grants" + depends on XEN_VIRTIO + help + Require virtio for Xen guests to use grant mappings. + This will avoid the need to give the backend the right to map all + of the guest memory. This will need support on the backend side + (e.g. qemu or kernel, depending on the virtio device types used). + endmenu diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c index fc0142484001..d1fae789dfad 100644 --- a/drivers/xen/grant-dma-ops.c +++ b/drivers/xen/grant-dma-ops.c @@ -11,6 +11,7 @@ #include <linux/dma-map-ops.h> #include <linux/of.h> #include <linux/pfn.h> +#include <linux/platform-feature.h> #include <linux/xarray.h> #include <xen/xen.h> #include <xen/xen-ops.h> @@ -27,6 +28,27 @@ static DEFINE_XARRAY(xen_grant_dma_devices); #define XEN_GRANT_DMA_ADDR_OFF (1ULL << 63) +static bool __initdata xen_virtio_grants; +static bool __initdata xen_virtio_grants_set; +static __init int parse_use_grants(char *arg) +{ + if (!strcmp(arg, "yes")) + xen_virtio_grants = true; + else if (!strcmp(arg, "no")) + xen_virtio_grants = false; + xen_virtio_grants_set = true; + + return 0; +} +early_param("xen_virtio_grant", parse_use_grants); + +void xen_set_restricted_virtio_memory_access(void) +{ + if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_virtio_grants || + (!xen_virtio_grants_set && xen_pv_domain())) + platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS); +} + static inline dma_addr_t grant_to_dma(grant_ref_t grant) { return XEN_GRANT_DMA_ADDR_OFF | ((dma_addr_t)grant << PAGE_SHIFT); diff --git a/include/xen/xen.h b/include/xen/xen.h index 0780a81e140d..e0b1d534366f 100644 --- a/include/xen/xen.h +++ b/include/xen/xen.h @@ -52,13 +52,11 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, extern u64 xen_saved_max_mem_size; #endif -#include <linux/platform-feature.h> - -static inline void xen_set_restricted_virtio_memory_access(void) -{ - if (IS_ENABLED(CONFIG_XEN_VIRTIO) && xen_domain()) - platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS); -} +#ifdef CONFIG_XEN_GRANT_DMA_OPS +void xen_set_restricted_virtio_memory_access(void); +#else +static inline void xen_set_restricted_virtio_memory_access(void) { } +#endif #ifdef CONFIG_XEN_UNPOPULATED_ALLOC int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages); -- 2.35.3
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