powerpc: book3s: kvm: Don't abuse host r2 in exit path

We don't use PACATOC for PR. Avoid updating HOST_R2 with PR
KVM mode when both HV and PR are enabled in the kernel. Without this we
get the below crash

(qemu)
Unable to handle kernel paging request for data at address 0xffffffffffff8310
Faulting instruction address: 0xc00000000001d5a4
cpu 0x2: Vector: 300 (Data Access) at [c0000001dc53aef0]
    pc: c00000000001d5a4: .vtime_delta.isra.1+0x34/0x1d0
    lr: c00000000001d760: .vtime_account_system+0x20/0x60
    sp: c0000001dc53b170
   msr: 8000000000009032
   dar: ffffffffffff8310
 dsisr: 40000000
  current = 0xc0000001d76c62d0
  paca    = 0xc00000000fef1100   softe: 0        irq_happened: 0x01
    pid   = 4472, comm = qemu-system-ppc
enter ? for help
[c0000001dc53b200] c00000000001d760 .vtime_account_system+0x20/0x60
[c0000001dc53b290] c00000000008d050 .kvmppc_handle_exit_pr+0x60/0xa50
[c0000001dc53b340] c00000000008f51c kvm_start_lightweight+0xb4/0xc4
[c0000001dc53b510] c00000000008cdf0 .kvmppc_vcpu_run_pr+0x150/0x2e0
[c0000001dc53b9e0] c00000000008341c .kvmppc_vcpu_run+0x2c/0x40
[c0000001dc53ba50] c000000000080af4 .kvm_arch_vcpu_ioctl_run+0x54/0x1b0
[c0000001dc53bae0] c00000000007b4c8 .kvm_vcpu_ioctl+0x478/0x730
[c0000001dc53bca0] c0000000002140cc .do_vfs_ioctl+0x4ac/0x770
[c0000001dc53bd80] c0000000002143e8 .SyS_ioctl+0x58/0xb0
[c0000001dc53be30] c000000000009e58 syscall_exit+0x0/0x98

Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h b/arch/powerpc/include/asm/kvm_book3s_asm.h
index 412b2f389474a3c6c9b27120cf6f208fc5b25c8a..192917d2239c4ed5a0eafd36b1206d176f0dddaa 100644 (file)
--- a/arch/powerpc/include/asm/kvm_book3s_asm.h
+++ b/arch/powerpc/include/asm/kvm_book3s_asm.h
@@ -79,6 +79,7 @@ struct kvmppc_host_state {
        ulong vmhandler;
        ulong scratch0;
        ulong scratch1;
+       ulong scratch2;
        u8 in_guest;
        u8 restore_hid5;
        u8 napping;

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 2ea5cc033ec8b633febb50071c43cfd31958f4f3..d3de01066f7dd786cd531614046b801ff7ebb18f 100644 (file)
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -576,6 +576,7 @@ int main(void)
        HSTATE_FIELD(HSTATE_VMHANDLER, vmhandler);
        HSTATE_FIELD(HSTATE_SCRATCH0, scratch0);
        HSTATE_FIELD(HSTATE_SCRATCH1, scratch1);
+       HSTATE_FIELD(HSTATE_SCRATCH2, scratch2);
        HSTATE_FIELD(HSTATE_IN_GUEST, in_guest);
        HSTATE_FIELD(HSTATE_RESTORE_HID5, restore_hid5);
        HSTATE_FIELD(HSTATE_NAPPING, napping);

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index bde28da696103963185197eac2756d14d56504cd..be4fa04a37c96d56d5f07d241395afe22e1627dd 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -754,15 +754,14 @@ kvmppc_interrupt_hv:
         * guest CR, R12 saved in shadow VCPU SCRATCH1/0
         * guest R13 saved in SPRN_SCRATCH0
         */
-       /* abuse host_r2 as third scratch area; we get r2 from PACATOC(r13) */
-       std     r9, HSTATE_HOST_R2(r13)
+       std     r9, HSTATE_SCRATCH2(r13)
 
        lbz     r9, HSTATE_IN_GUEST(r13)
        cmpwi   r9, KVM_GUEST_MODE_HOST_HV
        beq     kvmppc_bad_host_intr
 #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
        cmpwi   r9, KVM_GUEST_MODE_GUEST
-       ld      r9, HSTATE_HOST_R2(r13)
+       ld      r9, HSTATE_SCRATCH2(r13)
        beq     kvmppc_interrupt_pr
 #endif
        /* We're now back in the host but in guest MMU context */
@@ -782,7 +781,7 @@ kvmppc_interrupt_hv:
        std     r6, VCPU_GPR(R6)(r9)
        std     r7, VCPU_GPR(R7)(r9)
        std     r8, VCPU_GPR(R8)(r9)
-       ld      r0, HSTATE_HOST_R2(r13)
+       ld      r0, HSTATE_SCRATCH2(r13)
        std     r0, VCPU_GPR(R9)(r9)
        std     r10, VCPU_GPR(R10)(r9)
        std     r11, VCPU_GPR(R11)(r9)