KVM: PPC: Book3S HV: Save/restore XER in checkpointed register state

When switching from/to a guest that has a transaction in progress,
we need to save/restore the checkpointed register state.  Although
XER is part of the CPU state that gets checkpointed, the code that
does this saving and restoring doesn't save/restore XER.

This fixes it by saving and restoring the XER.  To allow userspace
to read/write the checkpointed XER value, we also add a new ONE_REG
specifier.

The visible effect of this bug is that the guest may see its XER
value being corrupted when it uses transactions.

Fixes: e4e38121507a ("KVM: PPC: Book3S HV: Add transactional memory support")
Fixes: 0a8eccefcb34 ("KVM: PPC: Book3S HV: Add missing code for transaction reclaim on guest exit")
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 739db9a..a7596e9 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2039,6 +2039,7 @@ registers, find a list below:
   PPC   | KVM_REG_PPC_TM_VSCR           | 32
   PPC   | KVM_REG_PPC_TM_DSCR           | 64
   PPC   | KVM_REG_PPC_TM_TAR            | 64
+  PPC   | KVM_REG_PPC_TM_XER            | 64
         |                               |
   MIPS  | KVM_REG_MIPS_R0               | 64
           ...

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 20ef27d..0e584ee 100644 (file)
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -565,6 +565,7 @@ struct kvm_vcpu_arch {
        u64 tfiar;
 
        u32 cr_tm;
+       u64 xer_tm;
        u64 lr_tm;
        u64 ctr_tm;
        u64 amr_tm;

diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index c93cf35..0fb1326 100644 (file)
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -596,6 +596,7 @@ struct kvm_get_htab_header {
 #define KVM_REG_PPC_TM_VSCR    (KVM_REG_PPC_TM | KVM_REG_SIZE_U32 | 0x67)
 #define KVM_REG_PPC_TM_DSCR    (KVM_REG_PPC_TM | KVM_REG_SIZE_U64 | 0x68)
 #define KVM_REG_PPC_TM_TAR     (KVM_REG_PPC_TM | KVM_REG_SIZE_U64 | 0x69)
+#define KVM_REG_PPC_TM_XER     (KVM_REG_PPC_TM | KVM_REG_SIZE_U64 | 0x6a)
 
 /* PPC64 eXternal Interrupt Controller Specification */
 #define KVM_DEV_XICS_GRP_SOURCES       1       /* 64-bit source attributes */

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index caec7bf..c833d88 100644 (file)
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -569,6 +569,7 @@ int main(void)
        DEFINE(VCPU_VRS_TM, offsetof(struct kvm_vcpu, arch.vr_tm.vr));
        DEFINE(VCPU_VRSAVE_TM, offsetof(struct kvm_vcpu, arch.vrsave_tm));
        DEFINE(VCPU_CR_TM, offsetof(struct kvm_vcpu, arch.cr_tm));
+       DEFINE(VCPU_XER_TM, offsetof(struct kvm_vcpu, arch.xer_tm));
        DEFINE(VCPU_LR_TM, offsetof(struct kvm_vcpu, arch.lr_tm));
        DEFINE(VCPU_CTR_TM, offsetof(struct kvm_vcpu, arch.ctr_tm));
        DEFINE(VCPU_AMR_TM, offsetof(struct kvm_vcpu, arch.amr_tm));

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 320a798..02f9aed 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1288,6 +1288,9 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
        case KVM_REG_PPC_TM_CR:
                *val = get_reg_val(id, vcpu->arch.cr_tm);
                break;
+       case KVM_REG_PPC_TM_XER:
+               *val = get_reg_val(id, vcpu->arch.xer_tm);
+               break;
        case KVM_REG_PPC_TM_LR:
                *val = get_reg_val(id, vcpu->arch.lr_tm);
                break;
@@ -1498,6 +1501,9 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
        case KVM_REG_PPC_TM_CR:
                vcpu->arch.cr_tm = set_reg_val(id, *val);
                break;
+       case KVM_REG_PPC_TM_XER:
+               vcpu->arch.xer_tm = set_reg_val(id, *val);
+               break;
        case KVM_REG_PPC_TM_LR:
                vcpu->arch.lr_tm = set_reg_val(id, *val);
                break;

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index c3c1d1b..6f81adb 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -2600,11 +2600,13 @@ kvmppc_save_tm:
        mfctr   r7
        mfspr   r8, SPRN_AMR
        mfspr   r10, SPRN_TAR
+       mfxer   r11
        std     r5, VCPU_LR_TM(r9)
        stw     r6, VCPU_CR_TM(r9)
        std     r7, VCPU_CTR_TM(r9)
        std     r8, VCPU_AMR_TM(r9)
        std     r10, VCPU_TAR_TM(r9)
+       std     r11, VCPU_XER_TM(r9)
 
        /* Restore r12 as trap number. */
        lwz     r12, VCPU_TRAP(r9)
@@ -2697,11 +2699,13 @@ kvmppc_restore_tm:
        ld      r7, VCPU_CTR_TM(r4)
        ld      r8, VCPU_AMR_TM(r4)
        ld      r9, VCPU_TAR_TM(r4)
+       ld      r10, VCPU_XER_TM(r4)
        mtlr    r5
        mtcr    r6
        mtctr   r7
        mtspr   SPRN_AMR, r8
        mtspr   SPRN_TAR, r9
+       mtxer   r10
 
        /*
         * Load up PPR and DSCR values but don't put them in the actual SPRs