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authorPaul Mackerras <paulus@samba.org>2012-11-19 22:57:20 +0000
committerAlexander Graf <agraf@suse.de>2012-12-06 01:33:57 +0100
commita2932923ccf63c419c77aaa18ac09be98f2c94d8 (patch)
tree391d9fc64d93bac26b442d7f2211dc99dbd10e67 /arch/powerpc/include/uapi
parent6b445ad4f839b06e68dd8e178e1168482ca20310 (diff)
downloadop-kernel-dev-a2932923ccf63c419c77aaa18ac09be98f2c94d8.zip
op-kernel-dev-a2932923ccf63c419c77aaa18ac09be98f2c94d8.tar.gz
KVM: PPC: Book3S HV: Provide a method for userspace to read and write the HPT
A new ioctl, KVM_PPC_GET_HTAB_FD, returns a file descriptor. Reads on this fd return the contents of the HPT (hashed page table), writes create and/or remove entries in the HPT. There is a new capability, KVM_CAP_PPC_HTAB_FD, to indicate the presence of the ioctl. The ioctl takes an argument structure with the index of the first HPT entry to read out and a set of flags. The flags indicate whether the user is intending to read or write the HPT, and whether to return all entries or only the "bolted" entries (those with the bolted bit, 0x10, set in the first doubleword). This is intended for use in implementing qemu's savevm/loadvm and for live migration. Therefore, on reads, the first pass returns information about all HPTEs (or all bolted HPTEs). When the first pass reaches the end of the HPT, it returns from the read. Subsequent reads only return information about HPTEs that have changed since they were last read. A read that finds no changed HPTEs in the HPT following where the last read finished will return 0 bytes. The format of the data provides a simple run-length compression of the invalid entries. Each block of data starts with a header that indicates the index (position in the HPT, which is just an array), the number of valid entries starting at that index (may be zero), and the number of invalid entries following those valid entries. The valid entries, 16 bytes each, follow the header. The invalid entries are not explicitly represented. Signed-off-by: Paul Mackerras <paulus@samba.org> [agraf: fix documentation] Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/include/uapi')
-rw-r--r--arch/powerpc/include/uapi/asm/kvm.h25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index b89ae4d..514883d 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -331,6 +331,31 @@ struct kvm_book3e_206_tlb_params {
__u32 reserved[8];
};
+/* For KVM_PPC_GET_HTAB_FD */
+struct kvm_get_htab_fd {
+ __u64 flags;
+ __u64 start_index;
+ __u64 reserved[2];
+};
+
+/* Values for kvm_get_htab_fd.flags */
+#define KVM_GET_HTAB_BOLTED_ONLY ((__u64)0x1)
+#define KVM_GET_HTAB_WRITE ((__u64)0x2)
+
+/*
+ * Data read on the file descriptor is formatted as a series of
+ * records, each consisting of a header followed by a series of
+ * `n_valid' HPTEs (16 bytes each), which are all valid. Following
+ * those valid HPTEs there are `n_invalid' invalid HPTEs, which
+ * are not represented explicitly in the stream. The same format
+ * is used for writing.
+ */
+struct kvm_get_htab_header {
+ __u32 index;
+ __u16 n_valid;
+ __u16 n_invalid;
+};
+
#define KVM_REG_PPC_HIOR (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0x1)
#define KVM_REG_PPC_IAC1 (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0x2)
#define KVM_REG_PPC_IAC2 (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0x3)
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