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| author | Alexander Graf <agraf@suse.de> | 2010-07-29 14:48:04 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-10-24 10:50:56 +0200 |
| commit | 819a63dc792b0888edd3eda306a9e1e049dcbb1c (patch) | |
| tree | 70599dcd83eb9892785cd9e7ca5d92534bedcdd7 /arch/powerpc/kernel/kvm.c | |
| parent | 92234722ed631f472f1c4d79d35d8e5cf6910002 (diff) | |
| download | linux-819a63dc792b0888edd3eda306a9e1e049dcbb1c.tar.bz2 | |
KVM: PPC: PV mtmsrd L=1
The PowerPC ISA has a special instruction for mtmsr that only changes the EE
and RI bits, namely the L=1 form.
Since that one is reasonably often occuring and simple to implement, let's
go with this first. Writing EE=0 is always just a store. Doing EE=1 also
requires us to check for pending interrupts and if necessary exit back to the
hypervisor.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/powerpc/kernel/kvm.c')
| -rw-r--r-- | arch/powerpc/kernel/kvm.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c index 239a70d750a2..717ab0dded25 100644 --- a/arch/powerpc/kernel/kvm.c +++ b/arch/powerpc/kernel/kvm.c @@ -63,6 +63,7 @@ #define KVM_INST_MTSPR_DSISR 0x7c1203a6 #define KVM_INST_TLBSYNC 0x7c00046c +#define KVM_INST_MTMSRD_L1 0x7c010164 static bool kvm_patching_worked = true; static char kvm_tmp[1024 * 1024]; @@ -138,6 +139,43 @@ static u32 *kvm_alloc(int len) return p; } +extern u32 kvm_emulate_mtmsrd_branch_offs; +extern u32 kvm_emulate_mtmsrd_reg_offs; +extern u32 kvm_emulate_mtmsrd_len; +extern u32 kvm_emulate_mtmsrd[]; + +static void kvm_patch_ins_mtmsrd(u32 *inst, u32 rt) +{ + u32 *p; + int distance_start; + int distance_end; + ulong next_inst; + + p = kvm_alloc(kvm_emulate_mtmsrd_len * 4); + if (!p) + return; + + /* Find out where we are and put everything there */ + distance_start = (ulong)p - (ulong)inst; + next_inst = ((ulong)inst + 4); + distance_end = next_inst - (ulong)&p[kvm_emulate_mtmsrd_branch_offs]; + + /* Make sure we only write valid b instructions */ + if (distance_start > KVM_INST_B_MAX) { + kvm_patching_worked = false; + return; + } + + /* Modify the chunk to fit the invocation */ + memcpy(p, kvm_emulate_mtmsrd, kvm_emulate_mtmsrd_len * 4); + p[kvm_emulate_mtmsrd_branch_offs] |= distance_end & KVM_INST_B_MASK; + p[kvm_emulate_mtmsrd_reg_offs] |= rt; + flush_icache_range((ulong)p, (ulong)p + kvm_emulate_mtmsrd_len * 4); + + /* Patch the invocation */ + kvm_patch_ins_b(inst, distance_start); +} + static void kvm_map_magic_page(void *data) { kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE, @@ -211,6 +249,13 @@ static void kvm_check_ins(u32 *inst) case KVM_INST_TLBSYNC: kvm_patch_ins_nop(inst); break; + + /* Rewrites */ + case KVM_INST_MTMSRD_L1: + /* We use r30 and r31 during the hook */ + if (get_rt(inst_rt) < 30) + kvm_patch_ins_mtmsrd(inst, inst_rt); + break; } switch (_inst) { |