From: Bhushan Bharat-R65777 <R65777@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: "kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Wood Scott-B07421 <B07421@freescale.com>
Subject: RE: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub support
Date: Fri, 29 Mar 2013 06:04:00 +0000 [thread overview]
Message-ID: <6A3DF150A5B70D4F9B66A25E3F7C888D06FB82BE@039-SN2MPN1-013.039d.mgd.msft.net> (raw)
In-Reply-To: <7355982C-05D1-4C58-A189-2F8F926AD11B@suse.de>
> -----Original Message-----
> From: Alexander Graf [mailto:agraf@suse.de]
> Sent: Thursday, March 28, 2013 10:06 PM
> To: Bhushan Bharat-R65777
> Cc: kvm-ppc@vger.kernel.org; kvm@vger.kernel.org; Wood Scott-B07421; Bhushan
> Bharat-R65777
> Subject: Re: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub support
>
>
> On 21.03.2013, at 07:25, Bharat Bhushan wrote:
>
> > From: Bharat Bhushan <bharat.bhushan@freescale.com>
> >
> > This patch adds the debug stub support on booke/bookehv.
> > Now QEMU debug stub can use hw breakpoint, watchpoint and software
> > breakpoint to debug guest.
> >
> > Debug registers are saved/restored on vcpu_put()/vcpu_get().
> > Also the debug registers are saved restored only if guest is using
> > debug resources.
> >
> > Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
> > ---
> > v2:
> > - save/restore in vcpu_get()/vcpu_put()
> > - some more minor cleanup based on review comments.
> >
> > arch/powerpc/include/asm/kvm_host.h | 10 ++
> > arch/powerpc/include/uapi/asm/kvm.h | 22 +++-
> > arch/powerpc/kvm/booke.c | 252 ++++++++++++++++++++++++++++++++---
> > arch/powerpc/kvm/e500_emulate.c | 10 ++
> > 4 files changed, 272 insertions(+), 22 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/kvm_host.h
> > b/arch/powerpc/include/asm/kvm_host.h
> > index f4ba881..8571952 100644
> > --- a/arch/powerpc/include/asm/kvm_host.h
> > +++ b/arch/powerpc/include/asm/kvm_host.h
> > @@ -504,7 +504,17 @@ struct kvm_vcpu_arch {
> > u32 mmucfg;
> > u32 epr;
> > u32 crit_save;
> > + /* guest debug registers*/
> > struct kvmppc_booke_debug_reg dbg_reg;
> > + /* shadow debug registers */
> > + struct kvmppc_booke_debug_reg shadow_dbg_reg;
> > + /* host debug registers*/
> > + struct kvmppc_booke_debug_reg host_dbg_reg;
> > + /*
> > + * Flag indicating that debug registers are used by guest
> > + * and requires save restore.
> > + */
> > + bool debug_save_restore;
> > #endif
> > gpa_t paddr_accessed;
> > gva_t vaddr_accessed;
> > diff --git a/arch/powerpc/include/uapi/asm/kvm.h
> > b/arch/powerpc/include/uapi/asm/kvm.h
> > index 15f9a00..d7ce449 100644
> > --- a/arch/powerpc/include/uapi/asm/kvm.h
> > +++ b/arch/powerpc/include/uapi/asm/kvm.h
> > @@ -25,6 +25,7 @@
> > /* Select powerpc specific features in <linux/kvm.h> */ #define
> > __KVM_HAVE_SPAPR_TCE #define __KVM_HAVE_PPC_SMT
> > +#define __KVM_HAVE_GUEST_DEBUG
> >
> > struct kvm_regs {
> > __u64 pc;
> > @@ -267,7 +268,24 @@ struct kvm_fpu {
> > __u64 fpr[32];
> > };
> >
> > +/*
> > + * Defines for h/w breakpoint, watchpoint (read, write or both) and
> > + * software breakpoint.
> > + * These are used as "type" in KVM_SET_GUEST_DEBUG ioctl and "status"
> > + * for KVM_DEBUG_EXIT.
> > + */
> > +#define KVMPPC_DEBUG_NONE 0x0
> > +#define KVMPPC_DEBUG_BREAKPOINT (1UL << 1)
> > +#define KVMPPC_DEBUG_WATCH_WRITE (1UL << 2)
> > +#define KVMPPC_DEBUG_WATCH_READ (1UL << 3)
> > struct kvm_debug_exit_arch {
> > + __u64 address;
> > + /*
> > + * exiting to userspace because of h/w breakpoint, watchpoint
> > + * (read, write or both) and software breakpoint.
> > + */
> > + __u32 status;
> > + __u32 reserved;
> > };
> >
> > /* for KVM_SET_GUEST_DEBUG */
> > @@ -279,10 +297,6 @@ struct kvm_guest_debug_arch {
> > * Type denotes h/w breakpoint, read watchpoint, write
> > * watchpoint or watchpoint (both read and write).
> > */
> > -#define KVMPPC_DEBUG_NOTYPE 0x0
> > -#define KVMPPC_DEBUG_BREAKPOINT (1UL << 1)
> > -#define KVMPPC_DEBUG_WATCH_WRITE (1UL << 2)
> > -#define KVMPPC_DEBUG_WATCH_READ (1UL << 3)
> > __u32 type;
> > __u32 reserved;
> > } bp[16];
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index
> > 1de93a8..bf20056 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -133,6 +133,30 @@ static void kvmppc_vcpu_sync_fpu(struct kvm_vcpu
> > *vcpu) #endif }
> >
> > +static void kvmppc_vcpu_sync_debug(struct kvm_vcpu *vcpu) {
> > + /* Synchronize guest's desire to get debug interrupts into shadow
> > +MSR */ #ifndef CONFIG_KVM_BOOKE_HV
> > + vcpu->arch.shadow_msr &= ~MSR_DE;
> > + vcpu->arch.shadow_msr |= vcpu->arch.shared->msr & MSR_DE; #endif
> > +
> > + /* Force enable debug interrupts when user space wants to debug */
> > + if (vcpu->guest_debug) {
> > +#ifdef CONFIG_KVM_BOOKE_HV
> > + /*
> > + * Since there is no shadow MSR, sync MSR_DE into the guest
> > + * visible MSR. Do not allow guest to change MSR[DE].
> > + */
> > + vcpu->arch.shared->msr |= MSR_DE;
> > + mtspr(SPRN_MSRP, mfspr(SPRN_MSRP) | MSRP_DEP);
>
> This mtspr should really just be a bit or in shadow_mspr when guest_debug gets
> enabled. It should automatically get synchronized as soon as the next
> vpcu_load() happens.
I think this is not required here as shadow_dbsr already have MSRP_DEP set.
Will setup shadow_msrp when setting guest_debug and clear shadow_msrp when guest_debug is cleared.
But that will also not be sufficient as it not sure when vcpu_load() will be called after the shadow_msrp is changed. So
When guest_debug is set in debug_ioctl()
/* Set MSRP_DEP in shadow_msrp so that guest cannot change MSR.DE. As shadow_msrp is loaded on vcpu_load(), and it is not guaranteed that vcpu_load() will be called just after debug_ioctl(), so also set MSRP_DEP in SPRN_MSRP. */
- shadow_msrp | MSRP_DEP;
- change SPRN_MSRP.MSRP_DEP as you do not know when vcpu_load() will be called?
When guest_debug is cleared in debug_ioctl()
/* Clear MSRP_DEP in shadow_msrp so that guest can change MSR.DE. As shadow_msrp is loaded on vcpu_load(), and it is not guaranteed that vcpu_load() will be called just after debug_ioctl(), so also clear MSRP_DEP in SPRN_MSRP. */
- shadow_msrp | MSRP_DEP;
- change SPRN_MSRP.MSRP_DEP as you do not know when vcpu_load() will be called?
>
> Also, what happens when user space disables guest_debug?
>
> > +#else
> > + vcpu->arch.shadow_msr |= MSR_DE;
> > + vcpu->arch.shared->msr &= ~MSR_DE;
> > +#endif
> > + }
> > +}
> > +
> > /*
> > * Helper function for "full" MSR writes. No need to call this if
> > only
> > * EE/CE/ME/DE/RI are changing.
> > @@ -150,6 +174,7 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u32 new_msr)
> > kvmppc_mmu_msr_notify(vcpu, old_msr);
> > kvmppc_vcpu_sync_spe(vcpu);
> > kvmppc_vcpu_sync_fpu(vcpu);
> > + kvmppc_vcpu_sync_debug(vcpu);
> > }
> >
> > static void kvmppc_booke_queue_irqprio(struct kvm_vcpu *vcpu, @@
> > -736,6 +761,9 @@ static int emulation_exit(struct kvm_run *run, struct
> kvm_vcpu *vcpu)
> > run->exit_reason = KVM_EXIT_DCR;
> > return RESUME_HOST;
> >
> > + case EMULATE_EXIT_USER:
> > + return RESUME_HOST;
>
> This should get folded into the previous patch or be a separate one.
ok
>
> > +
> > case EMULATE_FAIL:
> > printk(KERN_CRIT "%s: emulation at %lx failed (%08x)\n",
> > __func__, vcpu->arch.pc, vcpu->arch.last_inst); @@ -751,6
> > +779,30 @@ static int emulation_exit(struct kvm_run *run, struct kvm_vcpu
> *vcpu)
> > }
> > }
> >
> > +static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu
> > +*vcpu) {
> > + u32 dbsr = mfspr(SPRN_DBSR);
> > + mtspr(SPRN_DBSR, dbsr);
>
> This definitely deserves a comment :).
Ok.
> Also, are we non-preemptible here?
This is called from kvmppc_handle_exit and interrupts are enabled, so I think this can be preempted.
But I do not think there is any issue as we clear DBSR in vpu_put().
>
> > +
> > + run->debug.arch.status = 0;
> > + run->debug.arch.address = vcpu->arch.pc;
> > +
> > + if (dbsr & (DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4)) {
> > + run->debug.arch.status |= KVMPPC_DEBUG_BREAKPOINT;
> > + } else {
> > + if (dbsr & (DBSR_DAC1W | DBSR_DAC2W))
> > + run->debug.arch.status |= KVMPPC_DEBUG_WATCH_WRITE;
> > + else if (dbsr & (DBSR_DAC1R | DBSR_DAC2R))
> > + run->debug.arch.status |= KVMPPC_DEBUG_WATCH_READ;
> > + if (dbsr & (DBSR_DAC1R | DBSR_DAC1W))
> > + run->debug.arch.address = vcpu->arch.shadow_dbg_reg.dac[0];
> > + else if (dbsr & (DBSR_DAC2R | DBSR_DAC2W))
> > + run->debug.arch.address = vcpu->arch.shadow_dbg_reg.dac[1];
> > + }
> > +
> > + return RESUME_HOST;
>
> Shouldn't this check for guest_debug and only go to user space if it asked for
> debugging? Can't you just leave it at the old code for !guest_debug?
Will add, I thought that it is redundant as of now as debug interrupt in guest can come only when user space is debugging guest.
clear DBSR
if (!guest_debug)
return RESUME_GUEST;
>
> > +}
> > +
> > static void kvmppc_fill_pt_regs(struct pt_regs *regs) {
> > ulong r1, ip, msr, lr;
> > @@ -1110,18 +1162,10 @@ int kvmppc_handle_exit(struct kvm_run *run, struct
> kvm_vcpu *vcpu,
> > }
> >
> > case BOOKE_INTERRUPT_DEBUG: {
> > - u32 dbsr;
> > -
> > - vcpu->arch.pc = mfspr(SPRN_CSRR0);
> > -
> > - /* clear IAC events in DBSR register */
> > - dbsr = mfspr(SPRN_DBSR);
> > - dbsr &= DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4;
> > - mtspr(SPRN_DBSR, dbsr);
> > -
> > - run->exit_reason = KVM_EXIT_DEBUG;
> > + r = kvmppc_handle_debug(run, vcpu);
> > + if (r == RESUME_HOST)
> > + run->exit_reason = KVM_EXIT_DEBUG;
> > kvmppc_account_exit(vcpu, DEBUG_EXITS);
> > - r = RESUME_HOST;
> > break;
> > }
> >
> > @@ -1172,7 +1216,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> > kvmppc_set_msr(vcpu, 0);
> >
> > #ifndef CONFIG_KVM_BOOKE_HV
> > - vcpu->arch.shadow_msr = MSR_USER | MSR_DE | MSR_IS | MSR_DS;
> > + vcpu->arch.shadow_msr = MSR_USER | MSR_IS | MSR_DS;
> > vcpu->arch.shadow_pid = 1;
> > vcpu->arch.shared->msr = 0;
> > #endif
> > @@ -1527,12 +1571,6 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
> struct kvm_one_reg *reg)
> > return r;
> > }
> >
> > -int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> > - struct kvm_guest_debug *dbg)
> > -{
> > - return -EINVAL;
> > -}
> > -
> > int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu
> > *fpu) {
> > return -ENOTSUPP;
> > @@ -1638,16 +1676,194 @@ void kvmppc_decrementer_func(unsigned long data)
> > kvmppc_set_tsr_bits(vcpu, TSR_DIS);
> > }
> >
> > +static void kvmppc_booke_vcpu_put_debug_regs(struct kvm_vcpu *vcpu) {
> > + if (!vcpu->arch.debug_save_restore)
> > + return;
> > +
> > + /* Restore Host Context. Disable all debug events First */
> > + mtspr(SPRN_DBCR0, 0x0);
> > + /* Disable pending debug event by Clearing DBSR */
> > + mtspr(SPRN_DBSR, mfspr(SPRN_DBSR));
> > +
> > + mtspr(SPRN_DBCR1, vcpu->arch.host_dbg_reg.dbcr1);
> > + mtspr(SPRN_DBCR2, vcpu->arch.host_dbg_reg.dbcr2); #ifdef
> > +CONFIG_KVM_E500MC
> > + mtspr(SPRN_DBCR4, vcpu->arch.host_dbg_reg.dbcr4); #endif
> > + mtspr(SPRN_IAC1, vcpu->arch.host_dbg_reg.iac[0]);
> > + mtspr(SPRN_IAC2, vcpu->arch.host_dbg_reg.iac[1]); #if
> > +CONFIG_PPC_ADV_DEBUG_IACS > 2
> > + mtspr(SPRN_IAC3, vcpu->arch.host_dbg_reg.iac[2]);
> > + mtspr(SPRN_IAC4, vcpu->arch.host_dbg_reg.iac[3]); #endif
> > + mtspr(SPRN_DAC1, vcpu->arch.host_dbg_reg.dac[0]);
> > + mtspr(SPRN_DAC2, vcpu->arch.host_dbg_reg.dac[1]);
> > +
> > + /* Enable debug events after all other debug registers restored */
> > + mtspr(SPRN_DBCR0, vcpu->arch.host_dbg_reg.dbcr0);
>
> How does the normal debug register switching code work in Linux? Can't we just
> reuse that? Or rely on it to restore working state when another process gets
> scheduled in?
Good point, I can see debug registers loading in function __switch_to()->switch_booke_debug_regs() in file arch/powerpc/kernel/process.c.
So as long as assume that host will not use debug resources we can rely on this restore. But I am not sure that this is a fare assumption. As Scott earlier mentioned someone can use debug resource for kernel debugging also.
>
> > +
> > + /* Host debug register are restored */
> > + vcpu->arch.debug_save_restore = false; }
> > +
> > +static void kvmppc_booke_vcpu_load_debug_regs(struct kvm_vcpu *vcpu)
> > +{
> > + /*
> > + * Check whether guest still need debug resource, if not then there
> > + * is no need to resotre guest context.
>
> restore
>
> > + */
> > + if (!vcpu->arch.shadow_dbg_reg.dbcr0)
> > + return;
>
> Are we guaranteed that debugging is disabled here?
Ah, I should be clearing the hw DBCR0 and DBSR.
> We don't want to get debug
> exceptions that were meant for some other process.
>
> > +
> > + /*
> > + * Save Host debug register only after restore. If host debug
> > + * registers are saved and not restored then do not save again.
> > + */
> > + if (!vcpu->arch.debug_save_restore) {
> > + /* Save Host context */
> > + vcpu->arch.host_dbg_reg.dbcr0 = mfspr(SPRN_DBCR0);
> > + vcpu->arch.host_dbg_reg.dbcr1 = mfspr(SPRN_DBCR1);
> > + vcpu->arch.host_dbg_reg.dbcr2 = mfspr(SPRN_DBCR2); #ifdef
> > +CONFIG_KVM_E500MC
> > + vcpu->arch.host_dbg_reg.dbcr4 = mfspr(SPRN_DBCR4); #endif
> > + vcpu->arch.host_dbg_reg.iac[0] = mfspr(SPRN_IAC1);
> > + vcpu->arch.host_dbg_reg.iac[1] = mfspr(SPRN_IAC2); #if
> > +CONFIG_PPC_ADV_DEBUG_IACS > 2
> > + vcpu->arch.host_dbg_reg.iac[2] = mfspr(SPRN_IAC3);
> > + vcpu->arch.host_dbg_reg.iac[3] = mfspr(SPRN_IAC4); #endif
> > + vcpu->arch.host_dbg_reg.dac[0] = mfspr(SPRN_DAC1);
> > + vcpu->arch.host_dbg_reg.dac[1] = mfspr(SPRN_DAC2);
> > + vcpu->arch.debug_save_restore = true;
> > + }
> > +
> > + /* Restore Guest Context. Disable all debug events First */
> > + mtspr(SPRN_DBCR0, 0x0);
> > + /* Clear h/w DBSR */
> > + mtspr(SPRN_DBSR, mfspr(SPRN_DBSR));
> > +
> > + mtspr(SPRN_DBCR1, vcpu->arch.shadow_dbg_reg.dbcr1);
> > + mtspr(SPRN_DBCR2, vcpu->arch.shadow_dbg_reg.dbcr2); #ifdef
> > +CONFIG_KVM_E500MC
> > + mtspr(SPRN_DBCR4, vcpu->arch.shadow_dbg_reg.dbcr4); #endif
> > + mtspr(SPRN_IAC1, vcpu->arch.shadow_dbg_reg.iac[0]);
> > + mtspr(SPRN_IAC2, vcpu->arch.shadow_dbg_reg.iac[1]);
> > +#if CONFIG_PPC_ADV_DEBUG_IACS > 2
> > + mtspr(SPRN_IAC3, vcpu->arch.shadow_dbg_reg.iac[2]);
> > + mtspr(SPRN_IAC4, vcpu->arch.shadow_dbg_reg.iac[3]);
> > +#endif
> > + mtspr(SPRN_DAC1, vcpu->arch.shadow_dbg_reg.dac[0]);
> > + mtspr(SPRN_DAC2, vcpu->arch.shadow_dbg_reg.dac[1]);
> > +
> > + /* Enable debug events after other debug registers restored */
> > + mtspr(SPRN_DBCR0, vcpu->arch.shadow_dbg_reg.dbcr0); }
> > +
> > +int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> > + struct kvm_guest_debug *dbg)
> > +{
> > + struct kvmppc_booke_debug_reg *dbg_reg;
> > + int n, b = 0, w = 0;
> > + const u32 bp_code[] = {
> > + DBCR0_IAC1 | DBCR0_IDM,
> > + DBCR0_IAC2 | DBCR0_IDM,
> > + DBCR0_IAC3 | DBCR0_IDM,
> > + DBCR0_IAC4 | DBCR0_IDM
> > + };
> > + const u32 wp_code[] = {
> > + DBCR0_DAC1W | DBCR0_IDM,
> > + DBCR0_DAC2W | DBCR0_IDM,
> > + DBCR0_DAC1R | DBCR0_IDM,
> > + DBCR0_DAC2R | DBCR0_IDM
> > + };
> > +
> > + if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
> > + /* Clear All debug events */
> > + vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
> > + vcpu->guest_debug = 0;
>
> Ah, this is where we disable guest_debug. This needs to enable guest_debug for
> the guest again, so you need to remove the DE bit from shadow_msrp here.
>
> > + return 0;
> > + }
> > +
> > + vcpu->guest_debug = dbg->control;
> > + vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
> > + /* Set DBCR0_EDM in guest visible DBCR0 register. */
> > + vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM;
> > +
> > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
> > + vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
> > +
> > + if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) {
> > + /* Code below handles only HW breakpoints */
> > + kvmppc_booke_vcpu_load_debug_regs(vcpu);
> > + return 0;
> > + }
> > +
> > + dbg_reg = &(vcpu->arch.shadow_dbg_reg);
> > +
> > + /*
> > + * On BOOKE (e500v2); Set DBCR1 and DBCR2 to allow debug events
> > + * to occur when MSR.PR is set.
> > + * On BOOKE-HV (e500mc+); MSR.PR = 0 when guest is running. So we
> > + * should clear DBCR1 and DBCR2.
> > + */
> > +#ifdef CONFIG_KVM_BOOKE_HV
> > + dbg_reg->dbcr1 = 0;
> > + dbg_reg->dbcr2 = 0;
>
> Does that mean we can't debug guest user space?
Yes
>
> > +#else
> > + dbg_reg->dbcr1 = DBCR1_IAC1US | DBCR1_IAC2US | DBCR1_IAC3US |
> > + DBCR1_IAC4US;
> > + dbg_reg->dbcr2 = DBCR2_DAC1US | DBCR2_DAC2US; #endif
> > +
> > + for (n = 0; n < (KVMPPC_BOOKE_IAC_NUM + KVMPPC_BOOKE_DAC_NUM); n++) {
> > + u32 type = dbg->arch.bp[n].type;
> > +
> > + if (!type)
> > + break;
>
> Not continue?
I think wrong type should also mean error (INVALID)
>
> > +
> > + if (type & (KVMPPC_DEBUG_WATCH_READ |
> > + KVMPPC_DEBUG_WATCH_WRITE)) {
> > + if (w >= KVMPPC_BOOKE_DAC_NUM)
> > + continue;
>
> This should result in an error, no?
I do not think we need error, as gdb itself will through warning when trying to set more than required hardware breakpoint and watchpoint.
>
> > +
> > + if (type & KVMPPC_DEBUG_WATCH_READ)
> > + dbg_reg->dbcr0 |= wp_code[w + 2];
> > + if (type & KVMPPC_DEBUG_WATCH_WRITE)
> > + dbg_reg->dbcr0 |= wp_code[w];
> > +
> > + dbg_reg->dac[w] = dbg->arch.bp[n].addr;
> > + w++;
> > + } else if (type & KVMPPC_DEBUG_BREAKPOINT) {
> > + if (b >= KVMPPC_BOOKE_IAC_NUM)
> > + continue;
>
> Same here.
Same as above .
Thanks
-Bharat
>
> > +
> > + dbg_reg->dbcr0 |= bp_code[b];
> > + dbg_reg->iac[b] = dbg->arch.bp[n].addr;
> > + b++;
> > + }
> > + }
> > +
> > + kvmppc_booke_vcpu_load_debug_regs(vcpu);
> > + return 0;
> > +}
> > +
> > void kvmppc_booke_vcpu_load(struct kvm_vcpu *vcpu, int cpu) {
> > vcpu->cpu = smp_processor_id();
> > current->thread.kvm_vcpu = vcpu;
> > +
> > + kvmppc_booke_vcpu_load_debug_regs(vcpu);
> > }
> >
> > void kvmppc_booke_vcpu_put(struct kvm_vcpu *vcpu) {
> > current->thread.kvm_vcpu = NULL;
> > vcpu->cpu = -1;
> > +
> > + kvmppc_booke_vcpu_put_debug_regs(vcpu);
> > }
> >
> > int __init kvmppc_booke_init(void)
> > diff --git a/arch/powerpc/kvm/e500_emulate.c
> > b/arch/powerpc/kvm/e500_emulate.c index e78f353..cefdd38 100644
> > --- a/arch/powerpc/kvm/e500_emulate.c
> > +++ b/arch/powerpc/kvm/e500_emulate.c
> > @@ -26,6 +26,7 @@
> > #define XOP_TLBRE 946
> > #define XOP_TLBWE 978
> > #define XOP_TLBILX 18
> > +#define XOP_EHPRIV 270
> >
> > #ifdef CONFIG_KVM_E500MC
> > static int dbell2prio(ulong param)
> > @@ -130,6 +131,15 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct
> kvm_vcpu *vcpu,
> > emulated = kvmppc_e500_emul_tlbivax(vcpu, ea);
> > break;
> >
> > + case XOP_EHPRIV:
> > + run->exit_reason = KVM_EXIT_DEBUG;
> > + run->debug.arch.address = vcpu->arch.pc;
> > + run->debug.arch.status = 0;
> > + kvmppc_account_exit(vcpu, DEBUG_EXITS);
> > + emulated = EMULATE_EXIT_USER;
> > + *advance = 0;
> > + break;
> > +
>
> Looks good.
>
> I would appreciate if you could split this patch up a bit more
>
>
> Alex
>
WARNING: multiple messages have this Message-ID (diff)
From: Bhushan Bharat-R65777 <R65777@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: "kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Wood Scott-B07421 <B07421@freescale.com>
Subject: RE: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub support
Date: Fri, 29 Mar 2013 06:04:00 +0000 [thread overview]
Message-ID: <6A3DF150A5B70D4F9B66A25E3F7C888D06FB82BE@039-SN2MPN1-013.039d.mgd.msft.net> (raw)
In-Reply-To: <7355982C-05D1-4C58-A189-2F8F926AD11B@suse.de>
> -----Original Message-----
> From: Alexander Graf [mailto:agraf@suse.de]
> Sent: Thursday, March 28, 2013 10:06 PM
> To: Bhushan Bharat-R65777
> Cc: kvm-ppc@vger.kernel.org; kvm@vger.kernel.org; Wood Scott-B07421; Bhushan
> Bharat-R65777
> Subject: Re: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub support
>
>
> On 21.03.2013, at 07:25, Bharat Bhushan wrote:
>
> > From: Bharat Bhushan <bharat.bhushan@freescale.com>
> >
> > This patch adds the debug stub support on booke/bookehv.
> > Now QEMU debug stub can use hw breakpoint, watchpoint and software
> > breakpoint to debug guest.
> >
> > Debug registers are saved/restored on vcpu_put()/vcpu_get().
> > Also the debug registers are saved restored only if guest is using
> > debug resources.
> >
> > Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
> > ---
> > v2:
> > - save/restore in vcpu_get()/vcpu_put()
> > - some more minor cleanup based on review comments.
> >
> > arch/powerpc/include/asm/kvm_host.h | 10 ++
> > arch/powerpc/include/uapi/asm/kvm.h | 22 +++-
> > arch/powerpc/kvm/booke.c | 252 ++++++++++++++++++++++++++++++++---
> > arch/powerpc/kvm/e500_emulate.c | 10 ++
> > 4 files changed, 272 insertions(+), 22 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/kvm_host.h
> > b/arch/powerpc/include/asm/kvm_host.h
> > index f4ba881..8571952 100644
> > --- a/arch/powerpc/include/asm/kvm_host.h
> > +++ b/arch/powerpc/include/asm/kvm_host.h
> > @@ -504,7 +504,17 @@ struct kvm_vcpu_arch {
> > u32 mmucfg;
> > u32 epr;
> > u32 crit_save;
> > + /* guest debug registers*/
> > struct kvmppc_booke_debug_reg dbg_reg;
> > + /* shadow debug registers */
> > + struct kvmppc_booke_debug_reg shadow_dbg_reg;
> > + /* host debug registers*/
> > + struct kvmppc_booke_debug_reg host_dbg_reg;
> > + /*
> > + * Flag indicating that debug registers are used by guest
> > + * and requires save restore.
> > + */
> > + bool debug_save_restore;
> > #endif
> > gpa_t paddr_accessed;
> > gva_t vaddr_accessed;
> > diff --git a/arch/powerpc/include/uapi/asm/kvm.h
> > b/arch/powerpc/include/uapi/asm/kvm.h
> > index 15f9a00..d7ce449 100644
> > --- a/arch/powerpc/include/uapi/asm/kvm.h
> > +++ b/arch/powerpc/include/uapi/asm/kvm.h
> > @@ -25,6 +25,7 @@
> > /* Select powerpc specific features in <linux/kvm.h> */ #define
> > __KVM_HAVE_SPAPR_TCE #define __KVM_HAVE_PPC_SMT
> > +#define __KVM_HAVE_GUEST_DEBUG
> >
> > struct kvm_regs {
> > __u64 pc;
> > @@ -267,7 +268,24 @@ struct kvm_fpu {
> > __u64 fpr[32];
> > };
> >
> > +/*
> > + * Defines for h/w breakpoint, watchpoint (read, write or both) and
> > + * software breakpoint.
> > + * These are used as "type" in KVM_SET_GUEST_DEBUG ioctl and "status"
> > + * for KVM_DEBUG_EXIT.
> > + */
> > +#define KVMPPC_DEBUG_NONE 0x0
> > +#define KVMPPC_DEBUG_BREAKPOINT (1UL << 1)
> > +#define KVMPPC_DEBUG_WATCH_WRITE (1UL << 2)
> > +#define KVMPPC_DEBUG_WATCH_READ (1UL << 3)
> > struct kvm_debug_exit_arch {
> > + __u64 address;
> > + /*
> > + * exiting to userspace because of h/w breakpoint, watchpoint
> > + * (read, write or both) and software breakpoint.
> > + */
> > + __u32 status;
> > + __u32 reserved;
> > };
> >
> > /* for KVM_SET_GUEST_DEBUG */
> > @@ -279,10 +297,6 @@ struct kvm_guest_debug_arch {
> > * Type denotes h/w breakpoint, read watchpoint, write
> > * watchpoint or watchpoint (both read and write).
> > */
> > -#define KVMPPC_DEBUG_NOTYPE 0x0
> > -#define KVMPPC_DEBUG_BREAKPOINT (1UL << 1)
> > -#define KVMPPC_DEBUG_WATCH_WRITE (1UL << 2)
> > -#define KVMPPC_DEBUG_WATCH_READ (1UL << 3)
> > __u32 type;
> > __u32 reserved;
> > } bp[16];
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index
> > 1de93a8..bf20056 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -133,6 +133,30 @@ static void kvmppc_vcpu_sync_fpu(struct kvm_vcpu
> > *vcpu) #endif }
> >
> > +static void kvmppc_vcpu_sync_debug(struct kvm_vcpu *vcpu) {
> > + /* Synchronize guest's desire to get debug interrupts into shadow
> > +MSR */ #ifndef CONFIG_KVM_BOOKE_HV
> > + vcpu->arch.shadow_msr &= ~MSR_DE;
> > + vcpu->arch.shadow_msr |= vcpu->arch.shared->msr & MSR_DE; #endif
> > +
> > + /* Force enable debug interrupts when user space wants to debug */
> > + if (vcpu->guest_debug) {
> > +#ifdef CONFIG_KVM_BOOKE_HV
> > + /*
> > + * Since there is no shadow MSR, sync MSR_DE into the guest
> > + * visible MSR. Do not allow guest to change MSR[DE].
> > + */
> > + vcpu->arch.shared->msr |= MSR_DE;
> > + mtspr(SPRN_MSRP, mfspr(SPRN_MSRP) | MSRP_DEP);
>
> This mtspr should really just be a bit or in shadow_mspr when guest_debug gets
> enabled. It should automatically get synchronized as soon as the next
> vpcu_load() happens.
I think this is not required here as shadow_dbsr already have MSRP_DEP set.
Will setup shadow_msrp when setting guest_debug and clear shadow_msrp when guest_debug is cleared.
But that will also not be sufficient as it not sure when vcpu_load() will be called after the shadow_msrp is changed. So
When guest_debug is set in debug_ioctl()
/* Set MSRP_DEP in shadow_msrp so that guest cannot change MSR.DE. As shadow_msrp is loaded on vcpu_load(), and it is not guaranteed that vcpu_load() will be called just after debug_ioctl(), so also set MSRP_DEP in SPRN_MSRP. */
- shadow_msrp | MSRP_DEP;
- change SPRN_MSRP.MSRP_DEP as you do not know when vcpu_load() will be called?
When guest_debug is cleared in debug_ioctl()
/* Clear MSRP_DEP in shadow_msrp so that guest can change MSR.DE. As shadow_msrp is loaded on vcpu_load(), and it is not guaranteed that vcpu_load() will be called just after debug_ioctl(), so also clear MSRP_DEP in SPRN_MSRP. */
- shadow_msrp | MSRP_DEP;
- change SPRN_MSRP.MSRP_DEP as you do not know when vcpu_load() will be called?
>
> Also, what happens when user space disables guest_debug?
>
> > +#else
> > + vcpu->arch.shadow_msr |= MSR_DE;
> > + vcpu->arch.shared->msr &= ~MSR_DE;
> > +#endif
> > + }
> > +}
> > +
> > /*
> > * Helper function for "full" MSR writes. No need to call this if
> > only
> > * EE/CE/ME/DE/RI are changing.
> > @@ -150,6 +174,7 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u32 new_msr)
> > kvmppc_mmu_msr_notify(vcpu, old_msr);
> > kvmppc_vcpu_sync_spe(vcpu);
> > kvmppc_vcpu_sync_fpu(vcpu);
> > + kvmppc_vcpu_sync_debug(vcpu);
> > }
> >
> > static void kvmppc_booke_queue_irqprio(struct kvm_vcpu *vcpu, @@
> > -736,6 +761,9 @@ static int emulation_exit(struct kvm_run *run, struct
> kvm_vcpu *vcpu)
> > run->exit_reason = KVM_EXIT_DCR;
> > return RESUME_HOST;
> >
> > + case EMULATE_EXIT_USER:
> > + return RESUME_HOST;
>
> This should get folded into the previous patch or be a separate one.
ok
>
> > +
> > case EMULATE_FAIL:
> > printk(KERN_CRIT "%s: emulation at %lx failed (%08x)\n",
> > __func__, vcpu->arch.pc, vcpu->arch.last_inst); @@ -751,6
> > +779,30 @@ static int emulation_exit(struct kvm_run *run, struct kvm_vcpu
> *vcpu)
> > }
> > }
> >
> > +static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu
> > +*vcpu) {
> > + u32 dbsr = mfspr(SPRN_DBSR);
> > + mtspr(SPRN_DBSR, dbsr);
>
> This definitely deserves a comment :).
Ok.
> Also, are we non-preemptible here?
This is called from kvmppc_handle_exit and interrupts are enabled, so I think this can be preempted.
But I do not think there is any issue as we clear DBSR in vpu_put().
>
> > +
> > + run->debug.arch.status = 0;
> > + run->debug.arch.address = vcpu->arch.pc;
> > +
> > + if (dbsr & (DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4)) {
> > + run->debug.arch.status |= KVMPPC_DEBUG_BREAKPOINT;
> > + } else {
> > + if (dbsr & (DBSR_DAC1W | DBSR_DAC2W))
> > + run->debug.arch.status |= KVMPPC_DEBUG_WATCH_WRITE;
> > + else if (dbsr & (DBSR_DAC1R | DBSR_DAC2R))
> > + run->debug.arch.status |= KVMPPC_DEBUG_WATCH_READ;
> > + if (dbsr & (DBSR_DAC1R | DBSR_DAC1W))
> > + run->debug.arch.address = vcpu->arch.shadow_dbg_reg.dac[0];
> > + else if (dbsr & (DBSR_DAC2R | DBSR_DAC2W))
> > + run->debug.arch.address = vcpu->arch.shadow_dbg_reg.dac[1];
> > + }
> > +
> > + return RESUME_HOST;
>
> Shouldn't this check for guest_debug and only go to user space if it asked for
> debugging? Can't you just leave it at the old code for !guest_debug?
Will add, I thought that it is redundant as of now as debug interrupt in guest can come only when user space is debugging guest.
clear DBSR
if (!guest_debug)
return RESUME_GUEST;
>
> > +}
> > +
> > static void kvmppc_fill_pt_regs(struct pt_regs *regs) {
> > ulong r1, ip, msr, lr;
> > @@ -1110,18 +1162,10 @@ int kvmppc_handle_exit(struct kvm_run *run, struct
> kvm_vcpu *vcpu,
> > }
> >
> > case BOOKE_INTERRUPT_DEBUG: {
> > - u32 dbsr;
> > -
> > - vcpu->arch.pc = mfspr(SPRN_CSRR0);
> > -
> > - /* clear IAC events in DBSR register */
> > - dbsr = mfspr(SPRN_DBSR);
> > - dbsr &= DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4;
> > - mtspr(SPRN_DBSR, dbsr);
> > -
> > - run->exit_reason = KVM_EXIT_DEBUG;
> > + r = kvmppc_handle_debug(run, vcpu);
> > + if (r = RESUME_HOST)
> > + run->exit_reason = KVM_EXIT_DEBUG;
> > kvmppc_account_exit(vcpu, DEBUG_EXITS);
> > - r = RESUME_HOST;
> > break;
> > }
> >
> > @@ -1172,7 +1216,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> > kvmppc_set_msr(vcpu, 0);
> >
> > #ifndef CONFIG_KVM_BOOKE_HV
> > - vcpu->arch.shadow_msr = MSR_USER | MSR_DE | MSR_IS | MSR_DS;
> > + vcpu->arch.shadow_msr = MSR_USER | MSR_IS | MSR_DS;
> > vcpu->arch.shadow_pid = 1;
> > vcpu->arch.shared->msr = 0;
> > #endif
> > @@ -1527,12 +1571,6 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
> struct kvm_one_reg *reg)
> > return r;
> > }
> >
> > -int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> > - struct kvm_guest_debug *dbg)
> > -{
> > - return -EINVAL;
> > -}
> > -
> > int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu
> > *fpu) {
> > return -ENOTSUPP;
> > @@ -1638,16 +1676,194 @@ void kvmppc_decrementer_func(unsigned long data)
> > kvmppc_set_tsr_bits(vcpu, TSR_DIS);
> > }
> >
> > +static void kvmppc_booke_vcpu_put_debug_regs(struct kvm_vcpu *vcpu) {
> > + if (!vcpu->arch.debug_save_restore)
> > + return;
> > +
> > + /* Restore Host Context. Disable all debug events First */
> > + mtspr(SPRN_DBCR0, 0x0);
> > + /* Disable pending debug event by Clearing DBSR */
> > + mtspr(SPRN_DBSR, mfspr(SPRN_DBSR));
> > +
> > + mtspr(SPRN_DBCR1, vcpu->arch.host_dbg_reg.dbcr1);
> > + mtspr(SPRN_DBCR2, vcpu->arch.host_dbg_reg.dbcr2); #ifdef
> > +CONFIG_KVM_E500MC
> > + mtspr(SPRN_DBCR4, vcpu->arch.host_dbg_reg.dbcr4); #endif
> > + mtspr(SPRN_IAC1, vcpu->arch.host_dbg_reg.iac[0]);
> > + mtspr(SPRN_IAC2, vcpu->arch.host_dbg_reg.iac[1]); #if
> > +CONFIG_PPC_ADV_DEBUG_IACS > 2
> > + mtspr(SPRN_IAC3, vcpu->arch.host_dbg_reg.iac[2]);
> > + mtspr(SPRN_IAC4, vcpu->arch.host_dbg_reg.iac[3]); #endif
> > + mtspr(SPRN_DAC1, vcpu->arch.host_dbg_reg.dac[0]);
> > + mtspr(SPRN_DAC2, vcpu->arch.host_dbg_reg.dac[1]);
> > +
> > + /* Enable debug events after all other debug registers restored */
> > + mtspr(SPRN_DBCR0, vcpu->arch.host_dbg_reg.dbcr0);
>
> How does the normal debug register switching code work in Linux? Can't we just
> reuse that? Or rely on it to restore working state when another process gets
> scheduled in?
Good point, I can see debug registers loading in function __switch_to()->switch_booke_debug_regs() in file arch/powerpc/kernel/process.c.
So as long as assume that host will not use debug resources we can rely on this restore. But I am not sure that this is a fare assumption. As Scott earlier mentioned someone can use debug resource for kernel debugging also.
>
> > +
> > + /* Host debug register are restored */
> > + vcpu->arch.debug_save_restore = false; }
> > +
> > +static void kvmppc_booke_vcpu_load_debug_regs(struct kvm_vcpu *vcpu)
> > +{
> > + /*
> > + * Check whether guest still need debug resource, if not then there
> > + * is no need to resotre guest context.
>
> restore
>
> > + */
> > + if (!vcpu->arch.shadow_dbg_reg.dbcr0)
> > + return;
>
> Are we guaranteed that debugging is disabled here?
Ah, I should be clearing the hw DBCR0 and DBSR.
> We don't want to get debug
> exceptions that were meant for some other process.
>
> > +
> > + /*
> > + * Save Host debug register only after restore. If host debug
> > + * registers are saved and not restored then do not save again.
> > + */
> > + if (!vcpu->arch.debug_save_restore) {
> > + /* Save Host context */
> > + vcpu->arch.host_dbg_reg.dbcr0 = mfspr(SPRN_DBCR0);
> > + vcpu->arch.host_dbg_reg.dbcr1 = mfspr(SPRN_DBCR1);
> > + vcpu->arch.host_dbg_reg.dbcr2 = mfspr(SPRN_DBCR2); #ifdef
> > +CONFIG_KVM_E500MC
> > + vcpu->arch.host_dbg_reg.dbcr4 = mfspr(SPRN_DBCR4); #endif
> > + vcpu->arch.host_dbg_reg.iac[0] = mfspr(SPRN_IAC1);
> > + vcpu->arch.host_dbg_reg.iac[1] = mfspr(SPRN_IAC2); #if
> > +CONFIG_PPC_ADV_DEBUG_IACS > 2
> > + vcpu->arch.host_dbg_reg.iac[2] = mfspr(SPRN_IAC3);
> > + vcpu->arch.host_dbg_reg.iac[3] = mfspr(SPRN_IAC4); #endif
> > + vcpu->arch.host_dbg_reg.dac[0] = mfspr(SPRN_DAC1);
> > + vcpu->arch.host_dbg_reg.dac[1] = mfspr(SPRN_DAC2);
> > + vcpu->arch.debug_save_restore = true;
> > + }
> > +
> > + /* Restore Guest Context. Disable all debug events First */
> > + mtspr(SPRN_DBCR0, 0x0);
> > + /* Clear h/w DBSR */
> > + mtspr(SPRN_DBSR, mfspr(SPRN_DBSR));
> > +
> > + mtspr(SPRN_DBCR1, vcpu->arch.shadow_dbg_reg.dbcr1);
> > + mtspr(SPRN_DBCR2, vcpu->arch.shadow_dbg_reg.dbcr2); #ifdef
> > +CONFIG_KVM_E500MC
> > + mtspr(SPRN_DBCR4, vcpu->arch.shadow_dbg_reg.dbcr4); #endif
> > + mtspr(SPRN_IAC1, vcpu->arch.shadow_dbg_reg.iac[0]);
> > + mtspr(SPRN_IAC2, vcpu->arch.shadow_dbg_reg.iac[1]);
> > +#if CONFIG_PPC_ADV_DEBUG_IACS > 2
> > + mtspr(SPRN_IAC3, vcpu->arch.shadow_dbg_reg.iac[2]);
> > + mtspr(SPRN_IAC4, vcpu->arch.shadow_dbg_reg.iac[3]);
> > +#endif
> > + mtspr(SPRN_DAC1, vcpu->arch.shadow_dbg_reg.dac[0]);
> > + mtspr(SPRN_DAC2, vcpu->arch.shadow_dbg_reg.dac[1]);
> > +
> > + /* Enable debug events after other debug registers restored */
> > + mtspr(SPRN_DBCR0, vcpu->arch.shadow_dbg_reg.dbcr0); }
> > +
> > +int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> > + struct kvm_guest_debug *dbg)
> > +{
> > + struct kvmppc_booke_debug_reg *dbg_reg;
> > + int n, b = 0, w = 0;
> > + const u32 bp_code[] = {
> > + DBCR0_IAC1 | DBCR0_IDM,
> > + DBCR0_IAC2 | DBCR0_IDM,
> > + DBCR0_IAC3 | DBCR0_IDM,
> > + DBCR0_IAC4 | DBCR0_IDM
> > + };
> > + const u32 wp_code[] = {
> > + DBCR0_DAC1W | DBCR0_IDM,
> > + DBCR0_DAC2W | DBCR0_IDM,
> > + DBCR0_DAC1R | DBCR0_IDM,
> > + DBCR0_DAC2R | DBCR0_IDM
> > + };
> > +
> > + if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
> > + /* Clear All debug events */
> > + vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
> > + vcpu->guest_debug = 0;
>
> Ah, this is where we disable guest_debug. This needs to enable guest_debug for
> the guest again, so you need to remove the DE bit from shadow_msrp here.
>
> > + return 0;
> > + }
> > +
> > + vcpu->guest_debug = dbg->control;
> > + vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
> > + /* Set DBCR0_EDM in guest visible DBCR0 register. */
> > + vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM;
> > +
> > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
> > + vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
> > +
> > + if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) {
> > + /* Code below handles only HW breakpoints */
> > + kvmppc_booke_vcpu_load_debug_regs(vcpu);
> > + return 0;
> > + }
> > +
> > + dbg_reg = &(vcpu->arch.shadow_dbg_reg);
> > +
> > + /*
> > + * On BOOKE (e500v2); Set DBCR1 and DBCR2 to allow debug events
> > + * to occur when MSR.PR is set.
> > + * On BOOKE-HV (e500mc+); MSR.PR = 0 when guest is running. So we
> > + * should clear DBCR1 and DBCR2.
> > + */
> > +#ifdef CONFIG_KVM_BOOKE_HV
> > + dbg_reg->dbcr1 = 0;
> > + dbg_reg->dbcr2 = 0;
>
> Does that mean we can't debug guest user space?
Yes
>
> > +#else
> > + dbg_reg->dbcr1 = DBCR1_IAC1US | DBCR1_IAC2US | DBCR1_IAC3US |
> > + DBCR1_IAC4US;
> > + dbg_reg->dbcr2 = DBCR2_DAC1US | DBCR2_DAC2US; #endif
> > +
> > + for (n = 0; n < (KVMPPC_BOOKE_IAC_NUM + KVMPPC_BOOKE_DAC_NUM); n++) {
> > + u32 type = dbg->arch.bp[n].type;
> > +
> > + if (!type)
> > + break;
>
> Not continue?
I think wrong type should also mean error (INVALID)
>
> > +
> > + if (type & (KVMPPC_DEBUG_WATCH_READ |
> > + KVMPPC_DEBUG_WATCH_WRITE)) {
> > + if (w >= KVMPPC_BOOKE_DAC_NUM)
> > + continue;
>
> This should result in an error, no?
I do not think we need error, as gdb itself will through warning when trying to set more than required hardware breakpoint and watchpoint.
>
> > +
> > + if (type & KVMPPC_DEBUG_WATCH_READ)
> > + dbg_reg->dbcr0 |= wp_code[w + 2];
> > + if (type & KVMPPC_DEBUG_WATCH_WRITE)
> > + dbg_reg->dbcr0 |= wp_code[w];
> > +
> > + dbg_reg->dac[w] = dbg->arch.bp[n].addr;
> > + w++;
> > + } else if (type & KVMPPC_DEBUG_BREAKPOINT) {
> > + if (b >= KVMPPC_BOOKE_IAC_NUM)
> > + continue;
>
> Same here.
Same as above .
Thanks
-Bharat
>
> > +
> > + dbg_reg->dbcr0 |= bp_code[b];
> > + dbg_reg->iac[b] = dbg->arch.bp[n].addr;
> > + b++;
> > + }
> > + }
> > +
> > + kvmppc_booke_vcpu_load_debug_regs(vcpu);
> > + return 0;
> > +}
> > +
> > void kvmppc_booke_vcpu_load(struct kvm_vcpu *vcpu, int cpu) {
> > vcpu->cpu = smp_processor_id();
> > current->thread.kvm_vcpu = vcpu;
> > +
> > + kvmppc_booke_vcpu_load_debug_regs(vcpu);
> > }
> >
> > void kvmppc_booke_vcpu_put(struct kvm_vcpu *vcpu) {
> > current->thread.kvm_vcpu = NULL;
> > vcpu->cpu = -1;
> > +
> > + kvmppc_booke_vcpu_put_debug_regs(vcpu);
> > }
> >
> > int __init kvmppc_booke_init(void)
> > diff --git a/arch/powerpc/kvm/e500_emulate.c
> > b/arch/powerpc/kvm/e500_emulate.c index e78f353..cefdd38 100644
> > --- a/arch/powerpc/kvm/e500_emulate.c
> > +++ b/arch/powerpc/kvm/e500_emulate.c
> > @@ -26,6 +26,7 @@
> > #define XOP_TLBRE 946
> > #define XOP_TLBWE 978
> > #define XOP_TLBILX 18
> > +#define XOP_EHPRIV 270
> >
> > #ifdef CONFIG_KVM_E500MC
> > static int dbell2prio(ulong param)
> > @@ -130,6 +131,15 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct
> kvm_vcpu *vcpu,
> > emulated = kvmppc_e500_emul_tlbivax(vcpu, ea);
> > break;
> >
> > + case XOP_EHPRIV:
> > + run->exit_reason = KVM_EXIT_DEBUG;
> > + run->debug.arch.address = vcpu->arch.pc;
> > + run->debug.arch.status = 0;
> > + kvmppc_account_exit(vcpu, DEBUG_EXITS);
> > + emulated = EMULATE_EXIT_USER;
> > + *advance = 0;
> > + break;
> > +
>
> Looks good.
>
> I would appreciate if you could split this patch up a bit more
>
>
> Alex
>
next prev parent reply other threads:[~2013-03-29 6:04 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 6:24 [PATCH 0/4 v2] KVM :PPC: Userspace Debug support Bharat Bhushan
2013-03-21 6:36 ` Bharat Bhushan
2013-03-21 6:24 ` [PATCH 1/4 v2] Added ONE_REG interface for debug instruction Bharat Bhushan
2013-03-21 6:36 ` Bharat Bhushan
2013-03-29 1:55 ` Alexander Graf
2013-03-29 1:55 ` Alexander Graf
2013-03-21 6:24 ` [PATCH 2/4 v2] KVM: PPC: debug stub interface parameter defined Bharat Bhushan
2013-03-21 6:36 ` Bharat Bhushan
2013-03-29 1:55 ` Alexander Graf
2013-03-29 1:55 ` Alexander Graf
2013-03-29 3:08 ` Bhushan Bharat-R65777
2013-04-02 8:27 ` Alexander Graf
2013-04-02 8:27 ` Alexander Graf
2013-03-21 6:25 ` [PATCH 3/4 v2] Rename EMULATE_DO_PAPR to EMULATE_EXIT_USER Bharat Bhushan
2013-03-21 6:37 ` Bharat Bhushan
2013-03-28 14:05 ` Alexander Graf
2013-03-28 14:05 ` Alexander Graf
2013-03-21 6:25 ` [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub support Bharat Bhushan
2013-03-21 6:37 ` Bharat Bhushan
2013-03-28 16:36 ` Alexander Graf
2013-03-28 16:36 ` Alexander Graf
2013-03-29 6:04 ` Bhushan Bharat-R65777 [this message]
2013-03-29 6:04 ` Bhushan Bharat-R65777
2013-04-02 8:27 ` Alexander Graf
2013-04-02 8:27 ` Alexander Graf
2013-04-02 14:09 ` Bhushan Bharat-R65777
2013-04-02 14:09 ` Bhushan Bharat-R65777
2013-04-02 15:41 ` Alexander Graf
2013-04-02 15:41 ` Alexander Graf
2013-04-03 17:14 ` Bhushan Bharat-R65777
2013-04-03 17:14 ` Bhushan Bharat-R65777
2013-04-03 17:35 ` Alexander Graf
2013-04-03 17:35 ` Alexander Graf
2013-04-03 17:47 ` Bhushan Bharat-R65777
2013-04-03 17:47 ` Bhushan Bharat-R65777
2013-04-03 17:56 ` Alexander Graf
2013-04-03 17:56 ` Alexander Graf
2013-04-03 18:00 ` Bhushan Bharat-R65777
2013-04-03 18:00 ` Bhushan Bharat-R65777
2013-04-02 18:00 ` Scott Wood
2013-04-02 18:00 ` Scott Wood
2013-04-03 10:03 ` Bhushan Bharat-R65777
2013-04-03 10:03 ` Bhushan Bharat-R65777
2013-04-03 10:28 ` Alexander Graf
2013-04-03 10:28 ` Alexander Graf
2013-04-03 13:50 ` Bhushan Bharat-R65777
2013-04-03 13:50 ` Bhushan Bharat-R65777
2013-04-03 14:09 ` Alexander Graf
2013-04-03 14:09 ` Alexander Graf
2013-04-03 15:18 ` Bhushan Bharat-R65777
2013-04-03 15:18 ` Bhushan Bharat-R65777
2013-04-03 16:26 ` Alexander Graf
2013-04-03 16:26 ` Alexander Graf
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