Introduce mmap interface for a virtual processor, exposing a page for
setting and getting common registers while the VP is suspended.
This provides a more performant and convenient way to get and set these
registers in the context of a vmm's run-loop.
Co-developed-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
---
Documentation/virt/mshv/api.rst | 11 ++++
arch/x86/include/uapi/asm/hyperv-tlfs.h | 74 ++++++++++++++++++++++
include/asm-generic/hyperv-tlfs.h | 10 +++
include/linux/mshv.h | 1 +
include/uapi/asm-generic/hyperv-tlfs.h | 5 ++
include/uapi/linux/mshv.h | 12 ++++
virt/mshv/mshv_main.c | 82 +++++++++++++++++++++++++
7 files changed, 195 insertions(+)
diff --git a/Documentation/virt/mshv/api.rst b/Documentation/virt/mshv/api.rst
index 7fd75f248eff..89c276a8778f 100644
--- a/Documentation/virt/mshv/api.rst
+++ b/Documentation/virt/mshv/api.rst
@@ -149,3 +149,14 @@ HV_PARTITION_CREATION_FLAG_LAPIC_ENABLED
Get/set various vp state. Currently these can be used to get and set
emulated LAPIC state, and xsave data.
+3.10 mmap(vp)
+-------------
+:Type: vp mmap
+:Parameters: offset should be HV_VP_MMAP_REGISTERS_OFFSET
+:Returns: 0 on success
+
+Maps a page into userspace that can be used to get and set common registers
+while the vp is suspended.
+The page is laid out in struct hv_vp_register_page in asm/hyperv-tlfs.h.
+
+
diff --git a/arch/x86/include/uapi/asm/hyperv-tlfs.h b/arch/x86/include/uapi/asm/hyperv-tlfs.h
index 78758aedf23e..a241178567ff 100644
--- a/arch/x86/include/uapi/asm/hyperv-tlfs.h
+++ b/arch/x86/include/uapi/asm/hyperv-tlfs.h
@@ -1110,4 +1110,78 @@ struct hv_vp_state_data_xsave {
union hv_x64_xsave_xfem_register states;
};
+/* Bits for dirty mask of hv_vp_register_page */
+#define HV_X64_REGISTER_CLASS_GENERAL 0
+#define HV_X64_REGISTER_CLASS_IP 1
+#define HV_X64_REGISTER_CLASS_XMM 2
+#define HV_X64_REGISTER_CLASS_SEGMENT 3
+#define HV_X64_REGISTER_CLASS_FLAGS 4
+
+#define HV_VP_REGISTER_PAGE_VERSION_1 1u
+
+struct hv_vp_register_page {
+ __u16 version;
+ bool isvalid;
+ __u8 rsvdz;
+ __u32 dirty;
+ union {
+ struct {
+ __u64 rax;
+ __u64 rcx;
+ __u64 rdx;
+ __u64 rbx;
+ __u64 rsp;
+ __u64 rbp;
+ __u64 rsi;
+ __u64 rdi;
+ __u64 r8;
+ __u64 r9;
+ __u64 r10;
+ __u64 r11;
+ __u64 r12;
+ __u64 r13;
+ __u64 r14;
+ __u64 r15;
+ };
+
+ __u64 gp_registers[16];
+ };
+ __u64 rip;
+ __u64 rflags;
+ union {
+ struct {
+ struct hv_u128 xmm0;
+ struct hv_u128 xmm1;
+ struct hv_u128 xmm2;
+ struct hv_u128 xmm3;
+ struct hv_u128 xmm4;
+ struct hv_u128 xmm5;
+ };
+
+ struct hv_u128 xmm_registers[6];
+ };
+ union {
+ struct {
+ struct hv_x64_segment_register es;
+ struct hv_x64_segment_register cs;
+ struct hv_x64_segment_register ss;
+ struct hv_x64_segment_register ds;
+ struct hv_x64_segment_register fs;
+ struct hv_x64_segment_register gs;
+ };
+
+ struct hv_x64_segment_register segment_registers[6];
+ };
+ /* read only */
+ __u64 cr0;
+ __u64 cr3;
+ __u64 cr4;
+ __u64 cr8;
+ __u64 efer;
+ __u64 dr7;
+ union hv_x64_pending_interruption_register pending_interruption;
+ union hv_x64_interrupt_state_register interrupt_state;
+ __u64 instruction_emulation_hints;
+};
+
#endif
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 4bc59a0344ce..9eed4b869110 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -837,4 +837,14 @@ struct hv_set_vp_state_in {
union hv_input_set_vp_state_data data[];
};
+struct hv_map_vp_state_page_in {
+ u64 partition_id;
+ u32 vp_index;
+ enum hv_vp_state_page_type type;
+};
+
+struct hv_map_vp_state_page_out {
+ u64 map_location; /* page number */
+};
+
#endif
diff --git a/include/linux/mshv.h b/include/linux/mshv.h
index 3933d80294f1..33f4d0cfee11 100644
--- a/include/linux/mshv.h
+++ b/include/linux/mshv.h
@@ -20,6 +20,7 @@ struct mshv_vp {
u32 index;
struct mshv_partition *partition;
struct mutex mutex;
+ struct page *register_page;
struct {
struct semaphore sem;
struct task_struct *task;
diff --git a/include/uapi/asm-generic/hyperv-tlfs.h b/include/uapi/asm-generic/hyperv-tlfs.h
index b3c84c69b73f..a747f39b132a 100644
--- a/include/uapi/asm-generic/hyperv-tlfs.h
+++ b/include/uapi/asm-generic/hyperv-tlfs.h
@@ -92,4 +92,9 @@ enum hv_get_set_vp_state_type {
HV_GET_SET_VP_STATE_SYNTHETIC_TIMERS = 4,
};
+enum hv_vp_state_page_type {
+ HV_VP_STATE_PAGE_REGISTERS = 0,
+ HV_VP_STATE_PAGE_COUNT
+};
+
#endif
diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
index ae0bb64bbec3..8537ff29aee5 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h
@@ -13,6 +13,8 @@
#define MSHV_VERSION 0x0
+#define MSHV_VP_MMAP_REGISTERS_OFFSET (HV_VP_STATE_PAGE_REGISTERS * 0x1000)
+
struct mshv_create_partition {
__u64 flags;
struct hv_partition_creation_properties partition_creation_properties;
@@ -84,4 +86,14 @@ struct mshv_vp_state {
#define MSHV_GET_VP_STATE _IOWR(MSHV_IOCTL, 0x0A, struct mshv_vp_state)
#define MSHV_SET_VP_STATE _IOWR(MSHV_IOCTL, 0x0B, struct mshv_vp_state)
+/* register page mapping example:
+ * struct hv_vp_register_page *regs = mmap(NULL,
+ * 4096,
+ * PROT_READ | PROT_WRITE,
+ * MAP_SHARED,
+ * vp_fd,
+ * HV_VP_MMAP_REGISTERS_OFFSET);
+ * munmap(regs, 4096);
+ */
+
#endif
diff --git a/virt/mshv/mshv_main.c b/virt/mshv/mshv_main.c
index 70172d9488de..a597254fa4f4 100644
--- a/virt/mshv/mshv_main.c
+++ b/virt/mshv/mshv_main.c
@@ -43,11 +43,18 @@ static long mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned
static int mshv_dev_open(struct inode *inode, struct file *filp);
static int mshv_dev_release(struct inode *inode, struct file *filp);
static long mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
+static int mshv_vp_mmap(struct file *file, struct vm_area_struct *vma);
+static vm_fault_t mshv_vp_fault(struct vm_fault *vmf);
+
+static const struct vm_operations_struct mshv_vp_vm_ops = {
+ .fault = mshv_vp_fault,
+};
static const struct file_operations mshv_vp_fops = {
.release = mshv_vp_release,
.unlocked_ioctl = mshv_vp_ioctl,
.llseek = noop_llseek,
+ .mmap = mshv_vp_mmap,
};
static const struct file_operations mshv_partition_fops = {
@@ -499,6 +506,47 @@ hv_call_set_vp_registers(u32 vp_index,
return -hv_status_to_errno(status);
}
+static int
+hv_call_map_vp_state_page(u32 vp_index, u64 partition_id,
+ struct page **state_page)
+{
+ struct hv_map_vp_state_page_in *input;
+ struct hv_map_vp_state_page_out *output;
+ int status;
+ int ret;
+ unsigned long flags;
+
+ do {
+ local_irq_save(flags);
+ input = (struct hv_map_vp_state_page_in *)(*this_cpu_ptr(
+ hyperv_pcpu_input_arg));
+ output = (struct hv_map_vp_state_page_out *)(*this_cpu_ptr(
+ hyperv_pcpu_output_arg));
+
+ input->partition_id = partition_id;
+ input->vp_index = vp_index;
+ input->type = HV_VP_STATE_PAGE_REGISTERS;
+ status = hv_do_hypercall(HVCALL_MAP_VP_STATE_PAGE,
+ input, output);
+
+ if (status != HV_STATUS_INSUFFICIENT_MEMORY) {
+ if (status == HV_STATUS_SUCCESS)
+ *state_page = pfn_to_page(output->map_location);
+ else
+ pr_err("%s: %s\n", __func__,
+ hv_status_to_string(status));
+ local_irq_restore(flags);
+ ret = -hv_status_to_errno(status);
+ break;
+ }
+ local_irq_restore(flags);
+
+ ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id, 1);
+ } while (!ret);
+
+ return ret;
+}
+
static void
mshv_isr(void)
{
@@ -1155,6 +1203,40 @@ mshv_vp_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
return r;
}
+static vm_fault_t mshv_vp_fault(struct vm_fault *vmf)
+{
+ struct mshv_vp *vp = vmf->vma->vm_file->private_data;
+
+ vmf->page = vp->register_page;
+
+ return 0;
+}
+
+static int mshv_vp_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int ret;
+ struct mshv_vp *vp = file->private_data;
+
+ if (vma->vm_pgoff != MSHV_VP_MMAP_REGISTERS_OFFSET)
+ return -EINVAL;
+
+ if (mutex_lock_killable(&vp->mutex))
+ return -EINTR;
+
+ if (!vp->register_page) {
+ ret = hv_call_map_vp_state_page(vp->index,
+ vp->partition->id,
+ &vp->register_page);
+ if (ret)
+ return ret;
+ }
+
+ mutex_unlock(&vp->mutex);
+
+ vma->vm_ops = &mshv_vp_vm_ops;
+ return 0;
+}
+
static int
mshv_vp_release(struct inode *inode, struct file *filp)
{
--
2.25.1
