From 7810927760a0d16d7a41be4dab895fbbf9445bc0 Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Thu, 29 Jul 2010 14:48:05 +0200 Subject: [PATCH] KVM: PPC: PV mtmsrd L=0 and mtmsr There is also a form of mtmsr where all bits need to be addressed. While the PPC64 Linux kernel behaves resonably well here, on PPC32 we do not have an L=1 form. It does mtmsr even for simple things like only changing EE. So we need to hook into that one as well and check for a mask of bits that we deem safe to change from within guest context. Signed-off-by: Alexander Graf Signed-off-by: Avi Kivity --- arch/powerpc/kernel/kvm.c | 51 +++++++++++++++++++++++++ arch/powerpc/kernel/kvm_emul.S | 84 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 135 insertions(+) diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c index 717ab0d..8ac57e2 100644 --- a/arch/powerpc/kernel/kvm.c +++ b/arch/powerpc/kernel/kvm.c @@ -63,7 +63,9 @@ #define KVM_INST_MTSPR_DSISR 0x7c1203a6 #define KVM_INST_TLBSYNC 0x7c00046c +#define KVM_INST_MTMSRD_L0 0x7c000164 #define KVM_INST_MTMSRD_L1 0x7c010164 +#define KVM_INST_MTMSR 0x7c000124 static bool kvm_patching_worked = true; static char kvm_tmp[1024 * 1024]; @@ -176,6 +178,49 @@ static void kvm_patch_ins_mtmsrd(u32 *inst, u32 rt) kvm_patch_ins_b(inst, distance_start); } +extern u32 kvm_emulate_mtmsr_branch_offs; +extern u32 kvm_emulate_mtmsr_reg1_offs; +extern u32 kvm_emulate_mtmsr_reg2_offs; +extern u32 kvm_emulate_mtmsr_reg3_offs; +extern u32 kvm_emulate_mtmsr_orig_ins_offs; +extern u32 kvm_emulate_mtmsr_len; +extern u32 kvm_emulate_mtmsr[]; + +static void kvm_patch_ins_mtmsr(u32 *inst, u32 rt) +{ + u32 *p; + int distance_start; + int distance_end; + ulong next_inst; + + p = kvm_alloc(kvm_emulate_mtmsr_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_mtmsr_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_mtmsr, kvm_emulate_mtmsr_len * 4); + p[kvm_emulate_mtmsr_branch_offs] |= distance_end & KVM_INST_B_MASK; + p[kvm_emulate_mtmsr_reg1_offs] |= rt; + p[kvm_emulate_mtmsr_reg2_offs] |= rt; + p[kvm_emulate_mtmsr_reg3_offs] |= rt; + p[kvm_emulate_mtmsr_orig_ins_offs] = *inst; + flush_icache_range((ulong)p, (ulong)p + kvm_emulate_mtmsr_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, @@ -256,6 +301,12 @@ static void kvm_check_ins(u32 *inst) if (get_rt(inst_rt) < 30) kvm_patch_ins_mtmsrd(inst, inst_rt); break; + case KVM_INST_MTMSR: + case KVM_INST_MTMSRD_L0: + /* We use r30 and r31 during the hook */ + if (get_rt(inst_rt) < 30) + kvm_patch_ins_mtmsr(inst, inst_rt); + break; } switch (_inst) { diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S index 10dc4a6..8cd22f4 100644 --- a/arch/powerpc/kernel/kvm_emul.S +++ b/arch/powerpc/kernel/kvm_emul.S @@ -120,3 +120,87 @@ kvm_emulate_mtmsrd_reg_offs: .global kvm_emulate_mtmsrd_len kvm_emulate_mtmsrd_len: .long (kvm_emulate_mtmsrd_end - kvm_emulate_mtmsrd) / 4 + + +#define MSR_SAFE_BITS (MSR_EE | MSR_CE | MSR_ME | MSR_RI) +#define MSR_CRITICAL_BITS ~MSR_SAFE_BITS + +.global kvm_emulate_mtmsr +kvm_emulate_mtmsr: + + SCRATCH_SAVE + + /* Fetch old MSR in r31 */ + LL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0) + + /* Find the changed bits between old and new MSR */ +kvm_emulate_mtmsr_reg1: + xor r31, r0, r31 + + /* Check if we need to really do mtmsr */ + LOAD_REG_IMMEDIATE(r30, MSR_CRITICAL_BITS) + and. r31, r31, r30 + + /* No critical bits changed? Maybe we can stay in the guest. */ + beq maybe_stay_in_guest + +do_mtmsr: + + SCRATCH_RESTORE + + /* Just fire off the mtmsr if it's critical */ +kvm_emulate_mtmsr_orig_ins: + mtmsr r0 + + b kvm_emulate_mtmsr_branch + +maybe_stay_in_guest: + + /* Check if we have to fetch an interrupt */ + lwz r31, (KVM_MAGIC_PAGE + KVM_MAGIC_INT)(0) + cmpwi r31, 0 + beq+ no_mtmsr + + /* Check if we may trigger an interrupt */ +kvm_emulate_mtmsr_reg2: + andi. r31, r0, MSR_EE + beq no_mtmsr + + b do_mtmsr + +no_mtmsr: + + /* Put MSR into magic page because we don't call mtmsr */ +kvm_emulate_mtmsr_reg3: + STL64(r0, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0) + + SCRATCH_RESTORE + + /* Go back to caller */ +kvm_emulate_mtmsr_branch: + b . +kvm_emulate_mtmsr_end: + +.global kvm_emulate_mtmsr_branch_offs +kvm_emulate_mtmsr_branch_offs: + .long (kvm_emulate_mtmsr_branch - kvm_emulate_mtmsr) / 4 + +.global kvm_emulate_mtmsr_reg1_offs +kvm_emulate_mtmsr_reg1_offs: + .long (kvm_emulate_mtmsr_reg1 - kvm_emulate_mtmsr) / 4 + +.global kvm_emulate_mtmsr_reg2_offs +kvm_emulate_mtmsr_reg2_offs: + .long (kvm_emulate_mtmsr_reg2 - kvm_emulate_mtmsr) / 4 + +.global kvm_emulate_mtmsr_reg3_offs +kvm_emulate_mtmsr_reg3_offs: + .long (kvm_emulate_mtmsr_reg3 - kvm_emulate_mtmsr) / 4 + +.global kvm_emulate_mtmsr_orig_ins_offs +kvm_emulate_mtmsr_orig_ins_offs: + .long (kvm_emulate_mtmsr_orig_ins - kvm_emulate_mtmsr) / 4 + +.global kvm_emulate_mtmsr_len +kvm_emulate_mtmsr_len: + .long (kvm_emulate_mtmsr_end - kvm_emulate_mtmsr) / 4 -- 2.7.4