KVM: add initial support for KVM_SET_IOREGION

This vm ioctl adds or removes an ioregionfd MMIO/PIO region. Guest read and write accesses are dispatched through the given ioregionfd instead of returning from ioctl(KVM_RUN). Regions can be deleted by setting fds to -1. Signed-off-by: Elena Afanasova <eafanasova@gmail.com>
0day-ci · Dec 29, 2020 · 653378d · 653378d
1 parent e13a691
commit 653378d
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Showing 11 changed files with 350 additions and 3 deletions.
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
@@ -33,6 +33,7 @@ config KVM
 	select HAVE_KVM_IRQ_BYPASS
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_EVENTFD
+	select KVM_IOREGION
 	select KVM_ASYNC_PF
 	select USER_RETURN_NOTIFIER
 	select KVM_MMIO

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
@@ -12,6 +12,7 @@ KVM := ../../../virt/kvm
 kvm-y			+= $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o \
 				$(KVM)/eventfd.o $(KVM)/irqchip.o $(KVM)/vfio.o
 kvm-$(CONFIG_KVM_ASYNC_PF)	+= $(KVM)/async_pf.o
+kvm-$(CONFIG_KVM_IOREGION)	+= $(KVM)/ioregion.o
 
 kvm-y			+= x86.o emulate.o i8259.o irq.o lapic.o \
 			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
@@ -3739,6 +3739,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_X86_USER_SPACE_MSR:
 	case KVM_CAP_X86_MSR_FILTER:
 	case KVM_CAP_ENFORCE_PV_FEATURE_CPUID:
+	case KVM_CAP_IOREGIONFD:
 		r = 1;
 		break;
 	case KVM_CAP_SYNC_REGS:

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
@@ -470,6 +470,10 @@ struct kvm {
 		struct mutex      resampler_lock;
 	} irqfds;
 	struct list_head ioeventfds;
+#endif
+#ifdef CONFIG_KVM_IOREGION
+	struct list_head ioregions_mmio;
+	struct list_head ioregions_pio;
 #endif
 	struct kvm_vm_stat stat;
 	struct kvm_arch arch;
@@ -1262,6 +1266,19 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 
 #endif /* CONFIG_HAVE_KVM_EVENTFD */
 
+#ifdef CONFIG_KVM_IOREGION
+void kvm_ioregionfd_init(struct kvm *kvm);
+int kvm_ioregionfd(struct kvm *kvm, struct kvm_ioregion *args);
+
+#else
+
+static inline void kvm_ioregionfd_init(struct kvm *kvm) {}
+static inline int kvm_ioregionfd(struct kvm *kvm, struct kvm_ioregion *args)
+{
+	return -ENOSYS;
+}
+#endif
+
 void kvm_arch_irq_routing_update(struct kvm *kvm);
 
 static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
@@ -732,6 +732,27 @@ struct kvm_ioeventfd {
 	__u8  pad[36];
 };
 
+enum {
+	kvm_ioregion_flag_nr_pio,
+	kvm_ioregion_flag_nr_posted_writes,
+	kvm_ioregion_flag_nr_max,
+};
+
+#define KVM_IOREGION_PIO (1 << kvm_ioregion_flag_nr_pio)
+#define KVM_IOREGION_POSTED_WRITES (1 << kvm_ioregion_flag_nr_posted_writes)
+
+#define KVM_IOREGION_VALID_FLAG_MASK ((1 << kvm_ioregion_flag_nr_max) - 1)
+
+struct kvm_ioregion {
+	__u64 guest_paddr; /* guest physical address */
+	__u64 memory_size; /* bytes */
+	__u64 user_data;
+	__s32 rfd;
+	__s32 wfd;
+	__u32 flags;
+	__u8  pad[28];
+};
+
 #define KVM_X86_DISABLE_EXITS_MWAIT          (1 << 0)
 #define KVM_X86_DISABLE_EXITS_HLT            (1 << 1)
 #define KVM_X86_DISABLE_EXITS_PAUSE          (1 << 2)
@@ -1053,6 +1074,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_X86_USER_SPACE_MSR 188
 #define KVM_CAP_X86_MSR_FILTER 189
 #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190
+#define KVM_CAP_IOREGIONFD 191
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1308,6 +1330,7 @@ struct kvm_vfio_spapr_tce {
 					struct kvm_userspace_memory_region)
 #define KVM_SET_TSS_ADDR          _IO(KVMIO,   0x47)
 #define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO,  0x48, __u64)
+#define KVM_SET_IOREGION          _IOW(KVMIO,  0x49, struct kvm_ioregion)
 
 /* enable ucontrol for s390 */
 struct kvm_s390_ucas_mapping {

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
@@ -17,6 +17,9 @@ config HAVE_KVM_EVENTFD
        bool
        select EVENTFD
 
+config KVM_IOREGION
+       bool
+
 config KVM_MMIO
        bool
 

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
@@ -27,6 +27,7 @@
 #include <trace/events/kvm.h>
 
 #include <kvm/iodev.h>
+#include "ioregion.h"
 
 #ifdef CONFIG_HAVE_KVM_IRQFD
 
@@ -755,6 +756,23 @@ static const struct kvm_io_device_ops ioeventfd_ops = {
 	.destructor = ioeventfd_destructor,
 };
 
+#ifdef CONFIG_KVM_IOREGION
+/* assumes kvm->slots_lock held */
+bool kvm_eventfd_collides(struct kvm *kvm, int bus_idx,
+			  u64 start, u64 size)
+{
+	struct _ioeventfd *_p;
+
+	list_for_each_entry(_p, &kvm->ioeventfds, list)
+		if (_p->bus_idx == bus_idx &&
+		    overlap(start, size, _p->addr,
+			    !_p->length ? 8 : _p->length))
+			return true;
+
+	return false;
+}
+#endif
+
 /* assumes kvm->slots_lock held */
 static bool
 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
@@ -770,6 +788,13 @@ ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
 		       _p->datamatch == p->datamatch))))
 			return true;
 
+#ifdef CONFIG_KVM_IOREGION
+	if (p->bus_idx == KVM_MMIO_BUS || p->bus_idx == KVM_PIO_BUS)
+		if (kvm_ioregion_collides(kvm, p->bus_idx, p->addr,
+					  !p->length ? 8 : p->length))
+			return true;
+#endif
+
 	return false;
 }
 

diff --git a/virt/kvm/eventfd.h b/virt/kvm/eventfd.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __KVM_EVENTFD_H__
+#define __KVM_EVENTFD_H__
+
+#ifdef CONFIG_KVM_IOREGION
+bool kvm_eventfd_collides(struct kvm *kvm, int bus_idx, u64 start, u64 size);
+#else
+static inline bool
+kvm_eventfd_collides(struct kvm *kvm, int bus_idx, u64 start, u64 size)
+{
+	return false;
+}
+#endif
+#endif