KVM: PPC: Paravirtualize SPRG4-7, ESR, PIR, MASn

This allows additional registers to be accessed by the guest
in PR-mode KVM without trapping.

SPRG4-7 are readable from userspace.  On booke, KVM will sync
these registers when it enters the guest, so that accesses from
guest userspace will work.  The guest kernel, OTOH, must consistently
use either the real registers or the shared area between exits.  This
also applies to the already-paravirted SPRG3.

On non-booke, it's not clear to what extent SPRG4-7 are supported
(they're not architected for book3s, but exist on at least some classic
chips).  They are copied in the get/set regs ioctls, but I do not see any
non-booke emulation.  I also do not see any syncing with real registers
(in PR-mode) including the user-readable SPRG3.  This patch should not
make that situation any worse.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 29 insertions, 16 deletions

diff --git a/arch/powerpc/include/asm/kvm_e500.h b/arch/powerpc/include/asm/kvm_e500.h
index bc17441535f2..8cd50a514271 100644
--- a/arch/powerpc/include/asm/kvm_e500.h
+++ b/arch/powerpc/include/asm/kvm_e500.h
@@ -71,14 +71,6 @@ struct kvmppc_vcpu_e500 {
         u32 pid[E500_PID_NUM];
         u32 svr;
 
-        u32 mas0;
-        u32 mas1;
-        u32 mas2;
-        u64 mas7_3;
-        u32 mas4;
-        u32 mas5;
-        u32 mas6;
-
         /* vcpu id table */
         struct vcpu_id_table *idt;
 
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index bf8af5d5d5dc..bfd0c9912da5 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -318,10 +318,6 @@ struct kvm_vcpu_arch {
         u32 vrsave; /* also USPRG0 */
         u32 mmucr;
         ulong shadow_msr;
-        ulong sprg4;
-        ulong sprg5;
-        ulong sprg6;
-        ulong sprg7;
         ulong csrr0;
         ulong csrr1;
         ulong dsrr0;
@@ -329,7 +325,6 @@ struct kvm_vcpu_arch {
         ulong mcsrr0;
         ulong mcsrr1;
         ulong mcsr;
-        ulong esr;
         u32 dec;
         u32 decar;
         u32 tbl;
@@ -338,7 +333,6 @@ struct kvm_vcpu_arch {
         u32 tsr;
         u32 ivor[64];
         ulong ivpr;
-        u32 pir;
         u32 pvr;
 
         u32 shadow_pid;
diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
index 50533f9adf40..ece70fb36513 100644
--- a/arch/powerpc/include/asm/kvm_para.h
+++ b/arch/powerpc/include/asm/kvm_para.h
@@ -33,11 +33,35 @@ struct kvm_vcpu_arch_shared {
         __u64 sprg3;
         __u64 srr0;
         __u64 srr1;
-        __u64 dar;
+        __u64 dar;              /* dear on BookE */
         __u64 msr;
         __u32 dsisr;
         __u32 int_pending;      /* Tells the guest if we have an interrupt */
         __u32 sr[16];
+        __u32 mas0;
+        __u32 mas1;
+        __u64 mas7_3;
+        __u64 mas2;
+        __u32 mas4;
+        __u32 mas6;
+        __u32 esr;
+        __u32 pir;
+
+        /*
+         * SPRG4-7 are user-readable, so we can only keep these consistent
+         * between the shared area and the real registers when there's an
+         * intervening exit to KVM.  This also applies to SPRG3 on some
+         * chips.
+         *
+         * This suffices for access by guest userspace, since in PR-mode
+         * KVM, an exit must occur when changing the guest's MSR[PR].
+         * If the guest kernel writes to SPRG3-7 via the shared area, it
+         * must also use the shared area for reading while in kernel space.
+         */
+        __u64 sprg4;
+        __u64 sprg5;
+        __u64 sprg6;
+        __u64 sprg7;
 };
 
 #define KVM_SC_MAGIC_R0         0x4b564d21 /* "KVM!" */
@@ -47,7 +71,10 @@ struct kvm_vcpu_arch_shared {
 
 #define KVM_FEATURE_MAGIC_PAGE  1
 
-#define KVM_MAGIC_FEAT_SR       (1 << 0)
+#define KVM_MAGIC_FEAT_SR               (1 << 0)
+
+/* MASn, ESR, PIR, and high SPRGs */
+#define KVM_MAGIC_FEAT_MAS0_TO_SPRG7    (1 << 1)
 
 #ifdef __KERNEL__