[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 01/16] x86/xen: add xenhost_t interface
On 09.05.19 19:25, Ankur Arora wrote: Add xenhost_t which will serve as an abstraction over Xen interfaces. It co-exists with the PV/HVM/PVH abstractions (x86_init, hypervisor_x86, pv_ops etc) and is meant to capture mechanisms for communication with Xen so we could have different types of underlying Xen: regular, local, and nested. Also add xenhost_register() and stub registration in the various guest types. Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx> --- arch/x86/xen/Makefile | 1 + arch/x86/xen/enlighten_hvm.c | 13 +++++ arch/x86/xen/enlighten_pv.c | 16 ++++++ arch/x86/xen/enlighten_pvh.c | 12 +++++ arch/x86/xen/xenhost.c | 75 ++++++++++++++++++++++++++++ include/xen/xen.h | 3 ++ include/xen/xenhost.h | 95 ++++++++++++++++++++++++++++++++++++ 7 files changed, 215 insertions(+) create mode 100644 arch/x86/xen/xenhost.c create mode 100644 include/xen/xenhost.h diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile index 084de77a109e..564b4dddbc15 100644 --- a/arch/x86/xen/Makefile +++ b/arch/x86/xen/Makefile @@ -18,6 +18,7 @@ obj-y += mmu.o obj-y += time.o obj-y += grant-table.o obj-y += suspend.o +obj-y += xenhost.oobj-$(CONFIG_XEN_PVHVM) += enlighten_hvm.oobj-$(CONFIG_XEN_PVHVM) += mmu_hvm.o diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c index 0e75642d42a3..100452f4f44c 100644 --- a/arch/x86/xen/enlighten_hvm.c +++ b/arch/x86/xen/enlighten_hvm.c @@ -5,6 +5,7 @@ #include <linux/kexec.h> #include <linux/memblock.h>+#include <xen/xenhost.h>#include <xen/features.h> #include <xen/events.h> #include <xen/interface/memory.h> @@ -82,6 +83,12 @@ static void __init xen_hvm_init_mem_mapping(void) xen_vcpu_info_reset(0); }+xenhost_ops_t xh_hvm_ops = {+}; + +xenhost_ops_t xh_hvm_nested_ops = { +}; + static void __init init_hvm_pv_info(void) { int major, minor; @@ -179,6 +186,12 @@ static void __init xen_hvm_guest_init(void) { if (xen_pv_domain()) return; + /* + * We need only xenhost_r1 for HVM guests since they cannot be + * driver domain (?) or dom0. I think even HVM guests could (in theory) be driver domains. + */ + if (!xen_pvh_domain()) + xenhost_register(xenhost_r1, &xh_hvm_ops);init_hvm_pv_info(); diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.cindex c54a493e139a..bb6e811c1525 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -36,6 +36,7 @@#include <xen/xen.h>#include <xen/events.h> +#include <xen/xenhost.h> #include <xen/interface/xen.h> #include <xen/interface/version.h> #include <xen/interface/physdev.h> @@ -1188,6 +1189,12 @@ static void __init xen_dom0_set_legacy_features(void) x86_platform.legacy.rtc = 1; }+xenhost_ops_t xh_pv_ops = {+}; + +xenhost_ops_t xh_pv_nested_ops = { +}; + /* First C function to be called on Xen boot */ asmlinkage __visible void __init xen_start_kernel(void) { @@ -1198,6 +1205,15 @@ asmlinkage __visible void __init xen_start_kernel(void) if (!xen_start_info) return;+ xenhost_register(xenhost_r1, &xh_pv_ops);+ + /* + * Detect in some implementation defined manner whether this is + * nested or not. + */ + if (xen_driver_domain() && xen_nested()) + xenhost_register(xenhost_r2, &xh_pv_nested_ops); I don't think a driver domain other than dom0 "knows" this in the beginning. It will need to register xenhost_r2 in case it learns about a pv device from L0 hypervisor. + xen_domain_type = XEN_PV_DOMAIN; xen_start_flags = xen_start_info->flags;diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.cindex 35b7599d2d0b..826c296d27a3 100644 --- a/arch/x86/xen/enlighten_pvh.c +++ b/arch/x86/xen/enlighten_pvh.c @@ -8,6 +8,7 @@ #include <asm/e820/api.h>#include <xen/xen.h>+#include <xen/xenhost.h> #include <asm/xen/interface.h> #include <asm/xen/hypercall.h>@@ -21,11 +22,22 @@*/ bool xen_pvh __attribute__((section(".data"))) = 0;+extern xenhost_ops_t xh_hvm_ops, xh_hvm_nested_ops;+ void __init xen_pvh_init(void) { u32 msr; u64 pfn;+ xenhost_register(xenhost_r1, &xh_hvm_ops);+ + /* + * Detect in some implementation defined manner whether this is + * nested or not. + */ + if (xen_driver_domain() && xen_nested()) + xenhost_register(xenhost_r2, &xh_hvm_nested_ops); + xen_pvh = 1; xen_start_flags = pvh_start_info.flags;diff --git a/arch/x86/xen/xenhost.c b/arch/x86/xen/xenhost.cnew file mode 100644 index 000000000000..ca90acd7687e --- /dev/null +++ b/arch/x86/xen/xenhost.c @@ -0,0 +1,75 @@ +#include <linux/types.h> +#include <linux/bug.h> +#include <xen/xen.h> +#include <xen/xenhost.h> + +xenhost_t xenhosts[2]; +/* + * xh_default: interface to the regular hypervisor. xenhost_type is xenhost_r0 + * or xenhost_r1. + * + * xh_remote: interface to remote hypervisor. Needed for PV driver support on + * L1-dom0/driver-domain for nested Xen. xenhost_type is xenhost_r2. + */ +xenhost_t *xh_default = (xenhost_t *) &xenhosts[0]; +xenhost_t *xh_remote = (xenhost_t *) &xenhosts[1]; + +/* + * Exported for use of for_each_xenhost(). + */ +EXPORT_SYMBOL_GPL(xenhosts); + +/* + * Some places refer directly to a specific type of xenhost. + * This might be better as a macro though. + */ +EXPORT_SYMBOL_GPL(xh_default); +EXPORT_SYMBOL_GPL(xh_remote); + +void xenhost_register(enum xenhost_type type, xenhost_ops_t *ops) +{ + switch (type) { + case xenhost_r0: + case xenhost_r1: + BUG_ON(xh_default->type != xenhost_invalid); + + xh_default->type = type; + xh_default->ops = ops; + break; + case xenhost_r2: + BUG_ON(xh_remote->type != xenhost_invalid); + + /* + * We should have a default xenhost by the + * time xh_remote is registered. + */ + BUG_ON(!xh_default); + + xh_remote->type = type; + xh_remote->ops = ops; + break; + default: + BUG(); + } +} + +/* + * __xenhost_unregister: expected to be called only if there's an + * error early in the init. + */ +void __xenhost_unregister(enum xenhost_type type) +{ + switch (type) { + case xenhost_r0: + case xenhost_r1: + xh_default->type = xenhost_invalid; + xh_default->ops = NULL; + break; + case xenhost_r2: + xh_remote->type = xenhost_invalid; + xh_remote->ops = NULL; + break; + default: + BUG(); + } +} diff --git a/include/xen/xen.h b/include/xen/xen.h index 0e2156786ad2..540db8459536 100644 --- a/include/xen/xen.h +++ b/include/xen/xen.h @@ -42,6 +42,9 @@ extern struct hvm_start_info pvh_start_info; #define xen_initial_domain() (0) #endif /* CONFIG_XEN_DOM0 */+#define xen_driver_domain() xen_initial_domain()+#define xen_nested() 0 + struct bio_vec; bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, const struct bio_vec *vec2); diff --git a/include/xen/xenhost.h b/include/xen/xenhost.h new file mode 100644 index 000000000000..a58e883f144e --- /dev/null +++ b/include/xen/xenhost.h @@ -0,0 +1,95 @@ +#ifndef __XENHOST_H +#define __XENHOST_H + +/* + * Xenhost abstracts out the Xen interface. It co-exists with the PV/HVM/PVH + * abstractions (x86_init, hypervisor_x86, pv_ops etc) and is meant to + * expose ops for communication between the guest and Xen (hypercall, cpuid, + * shared_info/vcpu_info, evtchn, grant-table and on top of those, xenbus, ballooning), + * so these could differ based on the kind of underlying Xen: regular, local, + * and nested. + * + * Any call-sites which initiate communication with the hypervisor take + * xenhost_t * as a parameter and use the appropriate xenhost interface. + * + * Note, that the init for the nested xenhost (in the nested dom0 case, + * there are two) happens for each operation alongside the default xenhost + * (which remains similar to the one now) and is not deferred for later. + * This allows us to piggy-back on the non-trivial sequencing, inter-locking + * logic in the init of the default xenhost. + */ + +/* + * xenhost_type: specifies the controlling Xen interface. The notation, + * xenhost_r0, xenhost_r1, xenhost_r2 is meant to invoke hypervisor distance + * from the guest. This naming makes it hard to correlate the different things: In the nested case xenhost_r2 means L0 hypervisor, same as in the non-nested case xenhost_r1 does. What about: xenhost_local (instead xenhost_r0), xenhost_direct (instead xenhost_r1) and xenhost_nested (instead xenhost_r2). Or you use an integer to denote the distance enabling even deeper nesting levels (at least in theory). + * + * Note that the distance is relative, and so does not identify a specific + * hypervisor, just the role played by the interface: so, instance for L0-guest + * xenhost_r1 would be L0-Xen and for an L1-guest, L1-Xen. + */ +enum xenhost_type { + xenhost_invalid = 0, + /* + * xenhost_r1: the guest's frontend or backend drivers talking + * to a hypervisor one level removed. + * This is the ordinary, non-nested configuration as well as for the + * typical nested frontends and backends. + * + * The corresponding xenhost_t would continue to use the current + * interfaces, via a redirection layer. + */ + xenhost_r1, + + /* + * xenhost_r2: frontend drivers communicating with a hypervisor two + * levels removed: so L1-dom0-frontends communicating with L0-Xen. + * + * This is the nested-Xen configuration: L1-dom0-frontend drivers can + * now talk to L0-dom0-backend drivers via a separate xenhost_t. + */ + xenhost_r2, + + /* + * Local/Co-located case: backend drivers now run in the same address + * space as the hypervisor. The driver model remains same as + * xenhost_r1, but with slightly different interfaces. + * + * Any frontend guests of this hypervisor will continue to be + * xenhost_r1. + */ + xenhost_r0, +}; + +struct xenhost_ops; + +typedef struct { + enum xenhost_type type; + + struct xenhost_ops *ops; +} xenhost_t; + +typedef struct xenhost_ops { +} xenhost_ops_t; + +extern xenhost_t *xh_default, *xh_remote; +extern xenhost_t xenhosts[2]; Use a max nesting level define here and ... + +/* + * xenhost_register(): is called early in the guest's xen-init, after it detects + * in some implementation defined manner what kind of underlying xenhost or + * xenhosts exist. + * Specifies the type of xenhost being registered and the ops for that. + */ +void xenhost_register(enum xenhost_type type, xenhost_ops_t *ops); +void __xenhost_unregister(enum xenhost_type type); + + +/* + * Convoluted interface so we can do this without adding a loop counter. + */ +#define for_each_xenhost(xh) \ + for ((xh) = (xenhost_t **) &xenhosts[0]; \ + (((xh) - (xenhost_t **)&xenhosts) < 2) && (*xh)->type != xenhost_invalid; (xh)++) ... here, too. + +#endif /* __XENHOST_H */ Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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