On Mon, Jun 26, 2023 at 9:59 AM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
>
> After commit 45c7e8af4a5e3f0bea4ac209 ("MIPS: Remove KVM_TE support") we
> get a NULL pointer dereference when creating a KVM guest:
To be honest, a bug that needed 2 years to be reproduced is probably a
sign that KVM/MIPS has no users. Any objections to removing it
altogether?
Paolo
>
> [ 146.243409] Starting KVM with MIPS VZ extensions
> [ 149.849151] CPU 3 Unable to handle kernel paging request at virtual address 0000000000000300, epc == ffffffffc06356ec, ra == ffffffffc063568c
> [ 149.849177] Oops[#1]:
> [ 149.849182] CPU: 3 PID: 2265 Comm: qemu-system-mip Not tainted 6.4.0-rc3+ #1671
> [ 149.849188] Hardware name: THTF CX TL630 Series/THTF-LS3A4000-7A1000-ML4A, BIOS KL4.1F.TF.D.166.201225.R 12/25/2020
> [ 149.849192] $ 0 : 0000000000000000 000000007400cce0 0000000000400004 ffffffff8119c740
> [ 149.849209] $ 4 : 000000007400cce1 000000007400cce1 0000000000000000 0000000000000000
> [ 149.849221] $ 8 : 000000240058bb36 ffffffff81421ac0 0000000000000000 0000000000400dc0
> [ 149.849233] $12 : 9800000102a07cc8 ffffffff80e40e38 0000000000000001 0000000000400dc0
> [ 149.849245] $16 : 0000000000000000 9800000106cd0000 9800000106cd0000 9800000100cce000
> [ 149.849257] $20 : ffffffffc0632b28 ffffffffc05b31b0 9800000100ccca00 0000000000400000
> [ 149.849269] $24 : 9800000106cd09ce ffffffff802f69d0
> [ 149.849281] $28 : 9800000102a04000 9800000102a07cd0 98000001106a8000 ffffffffc063568c
> [ 149.849293] Hi : 00000335b2111e66
> [ 149.849295] Lo : 6668d90061ae0ae9
> [ 149.849298] epc : ffffffffc06356ec kvm_vz_vcpu_setup+0xc4/0x328 [kvm]
> [ 149.849324] ra : ffffffffc063568c kvm_vz_vcpu_setup+0x64/0x328 [kvm]
> [ 149.849336] Status: 7400cce3 KX SX UX KERNEL EXL IE
> [ 149.849351] Cause : 1000000c (ExcCode 03)
> [ 149.849354] BadVA : 0000000000000300
> [ 149.849357] PrId : 0014c004 (ICT Loongson-3)
> [ 149.849360] Modules linked in: kvm nfnetlink_queue nfnetlink_log nfnetlink fuse sha256_generic libsha256 cfg80211 rfkill binfmt_misc vfat fat snd_hda_codec_hdmi input_leds led_class snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_pcm snd_timer snd serio_raw xhci_pci radeon drm_suballoc_helper drm_display_helper xhci_hcd ip_tables x_tables
> [ 149.849432] Process qemu-system-mip (pid: 2265, threadinfo=00000000ae2982d2, task=0000000038e09ad4, tls=000000ffeba16030)
> [ 149.849439] Stack : 9800000000000003 9800000100ccca00 9800000100ccc000 ffffffffc062cef4
> [ 149.849453] 9800000102a07d18 c89b63a7ab338e00 0000000000000000 ffffffff811a0000
> [ 149.849465] 0000000000000000 9800000106cd0000 ffffffff80e59938 98000001106a8920
> [ 149.849476] ffffffff80e57f30 ffffffffc062854c ffffffff811a0000 9800000102bf4240
> [ 149.849488] ffffffffc05b0000 ffffffff80e3a798 000000ff78000000 000000ff78000010
> [ 149.849500] 0000000000000255 98000001021f7de0 98000001023f0078 ffffffff81434000
> [ 149.849511] 0000000000000000 0000000000000000 9800000102ae0000 980000025e92ae28
> [ 149.849523] 0000000000000000 c89b63a7ab338e00 0000000000000001 ffffffff8119dce0
> [ 149.849535] 000000ff78000010 ffffffff804f3d3c 9800000102a07eb0 0000000000000255
> [ 149.849546] 0000000000000000 ffffffff8049460c 000000ff78000010 0000000000000255
> [ 149.849558] ...
> [ 149.849565] Call Trace:
> [ 149.849567] [<ffffffffc06356ec>] kvm_vz_vcpu_setup+0xc4/0x328 [kvm]
> [ 149.849586] [<ffffffffc062cef4>] kvm_arch_vcpu_create+0x184/0x228 [kvm]
> [ 149.849605] [<ffffffffc062854c>] kvm_vm_ioctl+0x64c/0xf28 [kvm]
> [ 149.849623] [<ffffffff805209c0>] sys_ioctl+0xc8/0x118
> [ 149.849631] [<ffffffff80219eb0>] syscall_common+0x34/0x58
>
> The root cause is the deletion of kvm_mips_commpage_init() leaves vcpu->
> arch.cop0 NULL. So fix it by make cop0 from a pointer to an embed object.
>
> Fixes: 45c7e8af4a5e3f0bea4ac209 ("MIPS: Remove KVM_TE support")
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> ---
> arch/mips/include/asm/kvm_host.h | 6 +++---
> arch/mips/kvm/emulate.c | 22 +++++++++++-----------
> arch/mips/kvm/mips.c | 16 ++++++++--------
> arch/mips/kvm/trace.h | 8 ++++----
> arch/mips/kvm/vz.c | 20 ++++++++++----------
> 5 files changed, 36 insertions(+), 36 deletions(-)
>
> diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
> index 957121a495f0..04cedf9f8811 100644
> --- a/arch/mips/include/asm/kvm_host.h
> +++ b/arch/mips/include/asm/kvm_host.h
> @@ -317,7 +317,7 @@ struct kvm_vcpu_arch {
> unsigned int aux_inuse;
>
> /* COP0 State */
> - struct mips_coproc *cop0;
> + struct mips_coproc cop0;
>
> /* Resume PC after MMIO completion */
> unsigned long io_pc;
> @@ -698,7 +698,7 @@ static inline bool kvm_mips_guest_can_have_fpu(struct kvm_vcpu_arch *vcpu)
> static inline bool kvm_mips_guest_has_fpu(struct kvm_vcpu_arch *vcpu)
> {
> return kvm_mips_guest_can_have_fpu(vcpu) &&
> - kvm_read_c0_guest_config1(vcpu->cop0) & MIPS_CONF1_FP;
> + kvm_read_c0_guest_config1(&vcpu->cop0) & MIPS_CONF1_FP;
> }
>
> static inline bool kvm_mips_guest_can_have_msa(struct kvm_vcpu_arch *vcpu)
> @@ -710,7 +710,7 @@ static inline bool kvm_mips_guest_can_have_msa(struct kvm_vcpu_arch *vcpu)
> static inline bool kvm_mips_guest_has_msa(struct kvm_vcpu_arch *vcpu)
> {
> return kvm_mips_guest_can_have_msa(vcpu) &&
> - kvm_read_c0_guest_config3(vcpu->cop0) & MIPS_CONF3_MSA;
> + kvm_read_c0_guest_config3(&vcpu->cop0) & MIPS_CONF3_MSA;
> }
>
> struct kvm_mips_callbacks {
> diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
> index edaec93a1a1f..e64372b8f66a 100644
> --- a/arch/mips/kvm/emulate.c
> +++ b/arch/mips/kvm/emulate.c
> @@ -312,7 +312,7 @@ int kvm_get_badinstrp(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
> */
> int kvm_mips_count_disabled(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
>
> return (vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) ||
> (kvm_read_c0_guest_cause(cop0) & CAUSEF_DC);
> @@ -384,7 +384,7 @@ static inline ktime_t kvm_mips_count_time(struct kvm_vcpu *vcpu)
> */
> static u32 kvm_mips_read_count_running(struct kvm_vcpu *vcpu, ktime_t now)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> ktime_t expires, threshold;
> u32 count, compare;
> int running;
> @@ -444,7 +444,7 @@ static u32 kvm_mips_read_count_running(struct kvm_vcpu *vcpu, ktime_t now)
> */
> u32 kvm_mips_read_count(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
>
> /* If count disabled just read static copy of count */
> if (kvm_mips_count_disabled(vcpu))
> @@ -502,7 +502,7 @@ ktime_t kvm_mips_freeze_hrtimer(struct kvm_vcpu *vcpu, u32 *count)
> static void kvm_mips_resume_hrtimer(struct kvm_vcpu *vcpu,
> ktime_t now, u32 count)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> u32 compare;
> u64 delta;
> ktime_t expire;
> @@ -603,7 +603,7 @@ int kvm_mips_restore_hrtimer(struct kvm_vcpu *vcpu, ktime_t before,
> */
> void kvm_mips_write_count(struct kvm_vcpu *vcpu, u32 count)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> ktime_t now;
>
> /* Calculate bias */
> @@ -649,7 +649,7 @@ void kvm_mips_init_count(struct kvm_vcpu *vcpu, unsigned long count_hz)
> */
> int kvm_mips_set_count_hz(struct kvm_vcpu *vcpu, s64 count_hz)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> int dc;
> ktime_t now;
> u32 count;
> @@ -696,7 +696,7 @@ int kvm_mips_set_count_hz(struct kvm_vcpu *vcpu, s64 count_hz)
> */
> void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> int dc;
> u32 old_compare = kvm_read_c0_guest_compare(cop0);
> s32 delta = compare - old_compare;
> @@ -779,7 +779,7 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack)
> */
> static ktime_t kvm_mips_count_disable(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> u32 count;
> ktime_t now;
>
> @@ -806,7 +806,7 @@ static ktime_t kvm_mips_count_disable(struct kvm_vcpu *vcpu)
> */
> void kvm_mips_count_disable_cause(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
>
> kvm_set_c0_guest_cause(cop0, CAUSEF_DC);
> if (!(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC))
> @@ -826,7 +826,7 @@ void kvm_mips_count_disable_cause(struct kvm_vcpu *vcpu)
> */
> void kvm_mips_count_enable_cause(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> u32 count;
>
> kvm_clear_c0_guest_cause(cop0, CAUSEF_DC);
> @@ -852,7 +852,7 @@ void kvm_mips_count_enable_cause(struct kvm_vcpu *vcpu)
> */
> int kvm_mips_set_count_ctl(struct kvm_vcpu *vcpu, s64 count_ctl)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> s64 changed = count_ctl ^ vcpu->arch.count_ctl;
> s64 delta;
> ktime_t expire, now;
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 884be4ef99dc..aa5583a7b05b 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -649,7 +649,7 @@ static int kvm_mips_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices)
> static int kvm_mips_get_reg(struct kvm_vcpu *vcpu,
> const struct kvm_one_reg *reg)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> struct mips_fpu_struct *fpu = &vcpu->arch.fpu;
> int ret;
> s64 v;
> @@ -761,7 +761,7 @@ static int kvm_mips_get_reg(struct kvm_vcpu *vcpu,
> static int kvm_mips_set_reg(struct kvm_vcpu *vcpu,
> const struct kvm_one_reg *reg)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> struct mips_fpu_struct *fpu = &vcpu->arch.fpu;
> s64 v;
> s64 vs[2];
> @@ -1086,7 +1086,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> {
> return kvm_mips_pending_timer(vcpu) ||
> - kvm_read_c0_guest_cause(vcpu->arch.cop0) & C_TI;
> + kvm_read_c0_guest_cause(&vcpu->arch.cop0) & C_TI;
> }
>
> int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu)
> @@ -1110,7 +1110,7 @@ int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu)
> kvm_debug("\thi: 0x%08lx\n", vcpu->arch.hi);
> kvm_debug("\tlo: 0x%08lx\n", vcpu->arch.lo);
>
> - cop0 = vcpu->arch.cop0;
> + cop0 = &vcpu->arch.cop0;
> kvm_debug("\tStatus: 0x%08x, Cause: 0x%08x\n",
> kvm_read_c0_guest_status(cop0),
> kvm_read_c0_guest_cause(cop0));
> @@ -1232,7 +1232,7 @@ static int __kvm_mips_handle_exit(struct kvm_vcpu *vcpu)
>
> case EXCCODE_TLBS:
> kvm_debug("TLB ST fault: cause %#x, status %#x, PC: %p, BadVaddr: %#lx\n",
> - cause, kvm_read_c0_guest_status(vcpu->arch.cop0), opc,
> + cause, kvm_read_c0_guest_status(&vcpu->arch.cop0), opc,
> badvaddr);
>
> ++vcpu->stat.tlbmiss_st_exits;
> @@ -1304,7 +1304,7 @@ static int __kvm_mips_handle_exit(struct kvm_vcpu *vcpu)
> kvm_get_badinstr(opc, vcpu, &inst);
> kvm_err("Exception Code: %d, not yet handled, @ PC: %p, inst: 0x%08x BadVaddr: %#lx Status: %#x\n",
> exccode, opc, inst, badvaddr,
> - kvm_read_c0_guest_status(vcpu->arch.cop0));
> + kvm_read_c0_guest_status(&vcpu->arch.cop0));
> kvm_arch_vcpu_dump_regs(vcpu);
> run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> ret = RESUME_HOST;
> @@ -1377,7 +1377,7 @@ int noinstr kvm_mips_handle_exit(struct kvm_vcpu *vcpu)
> /* Enable FPU for guest and restore context */
> void kvm_own_fpu(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> unsigned int sr, cfg5;
>
> preempt_disable();
> @@ -1421,7 +1421,7 @@ void kvm_own_fpu(struct kvm_vcpu *vcpu)
> /* Enable MSA for guest and restore context */
> void kvm_own_msa(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> unsigned int sr, cfg5;
>
> preempt_disable();
> diff --git a/arch/mips/kvm/trace.h b/arch/mips/kvm/trace.h
> index a8c7fd7bf6d2..136c3535a1cb 100644
> --- a/arch/mips/kvm/trace.h
> +++ b/arch/mips/kvm/trace.h
> @@ -322,11 +322,11 @@ TRACE_EVENT_FN(kvm_guest_mode_change,
> ),
>
> TP_fast_assign(
> - __entry->epc = kvm_read_c0_guest_epc(vcpu->arch.cop0);
> + __entry->epc = kvm_read_c0_guest_epc(&vcpu->arch.cop0);
> __entry->pc = vcpu->arch.pc;
> - __entry->badvaddr = kvm_read_c0_guest_badvaddr(vcpu->arch.cop0);
> - __entry->status = kvm_read_c0_guest_status(vcpu->arch.cop0);
> - __entry->cause = kvm_read_c0_guest_cause(vcpu->arch.cop0);
> + __entry->badvaddr = kvm_read_c0_guest_badvaddr(&vcpu->arch.cop0);
> + __entry->status = kvm_read_c0_guest_status(&vcpu->arch.cop0);
> + __entry->cause = kvm_read_c0_guest_cause(&vcpu->arch.cop0);
> ),
>
> TP_printk("EPC: 0x%08lx PC: 0x%08lx Status: 0x%08x Cause: 0x%08x BadVAddr: 0x%08lx",
> diff --git a/arch/mips/kvm/vz.c b/arch/mips/kvm/vz.c
> index 3d21cbfa7443..99d5a71e4300 100644
> --- a/arch/mips/kvm/vz.c
> +++ b/arch/mips/kvm/vz.c
> @@ -422,7 +422,7 @@ static void _kvm_vz_restore_htimer(struct kvm_vcpu *vcpu,
> */
> static void kvm_vz_restore_timer(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> u32 cause, compare;
>
> compare = kvm_read_sw_gc0_compare(cop0);
> @@ -517,7 +517,7 @@ static void _kvm_vz_save_htimer(struct kvm_vcpu *vcpu,
> */
> static void kvm_vz_save_timer(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> u32 gctl0, compare, cause;
>
> gctl0 = read_c0_guestctl0();
> @@ -863,7 +863,7 @@ static unsigned long mips_process_maar(unsigned int op, unsigned long val)
>
> static void kvm_write_maari(struct kvm_vcpu *vcpu, unsigned long val)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
>
> val &= MIPS_MAARI_INDEX;
> if (val == MIPS_MAARI_INDEX)
> @@ -876,7 +876,7 @@ static enum emulation_result kvm_vz_gpsi_cop0(union mips_instruction inst,
> u32 *opc, u32 cause,
> struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> enum emulation_result er = EMULATE_DONE;
> u32 rt, rd, sel;
> unsigned long curr_pc;
> @@ -1911,7 +1911,7 @@ static int kvm_vz_get_one_reg(struct kvm_vcpu *vcpu,
> const struct kvm_one_reg *reg,
> s64 *v)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> unsigned int idx;
>
> switch (reg->id) {
> @@ -2081,7 +2081,7 @@ static int kvm_vz_get_one_reg(struct kvm_vcpu *vcpu,
> case KVM_REG_MIPS_CP0_MAARI:
> if (!cpu_guest_has_maar || cpu_guest_has_dyn_maar)
> return -EINVAL;
> - *v = kvm_read_sw_gc0_maari(vcpu->arch.cop0);
> + *v = kvm_read_sw_gc0_maari(&vcpu->arch.cop0);
> break;
> #ifdef CONFIG_64BIT
> case KVM_REG_MIPS_CP0_XCONTEXT:
> @@ -2135,7 +2135,7 @@ static int kvm_vz_set_one_reg(struct kvm_vcpu *vcpu,
> const struct kvm_one_reg *reg,
> s64 v)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> unsigned int idx;
> int ret = 0;
> unsigned int cur, change;
> @@ -2562,7 +2562,7 @@ static void kvm_vz_vcpu_load_tlb(struct kvm_vcpu *vcpu, int cpu)
>
> static int kvm_vz_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> bool migrated, all;
>
> /*
> @@ -2704,7 +2704,7 @@ static int kvm_vz_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>
> static int kvm_vz_vcpu_put(struct kvm_vcpu *vcpu, int cpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
>
> if (current->flags & PF_VCPU)
> kvm_vz_vcpu_save_wired(vcpu);
> @@ -3076,7 +3076,7 @@ static void kvm_vz_vcpu_uninit(struct kvm_vcpu *vcpu)
>
> static int kvm_vz_vcpu_setup(struct kvm_vcpu *vcpu)
> {
> - struct mips_coproc *cop0 = vcpu->arch.cop0;
> + struct mips_coproc *cop0 = &vcpu->arch.cop0;
> unsigned long count_hz = 100*1000*1000; /* default to 100 MHz */
>
> /*
> --
> 2.39.3
>
