Re: [PATCH V4 1/2] Add code to track call origin for msr assignment.

[Gleb Natapov <gleb@redhat.com>]

On Tue, Nov 27, 2012 at 06:19:21PM +0000, Auld, Will wrote:
> Gleb,
> 
> This last change to emulator_set_msr() was wrong as you point out. I will change it back to what it was in V3 with the exception of fixing the bool that Marcelo pointed out. 
> 
> However, the change of:
> 
> struct kvm_x86_ops {...
> 	int (*set_msr)(struct kvm_vcpu *vcpu, struct msr_data *msr);
> ...
> };
> 
> To match emulator_set_msr() prototype seems wrong because emulator_set_msr() is used with the following structure: 
> 
> struct x86_emulate_ops {...
> 	int (*set_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
> ...
> };
> 
> Rather than with "struct kvm_x86_ops" and I don't see that these two need to agree. In fact, they don't agree in the first parameter which proceeds my mucking.
> 
> If this is correct I will not make any changes to "struct kvm_x86_ops" set_msr() prototype (remain as is in V4).
> 
> Does this make since? Do you agree?
> 
Ugh, yeah. I looked at the wrong structure. Disregard this. Change true
to false in V3. Sorry about the confusion.

> Will
> 
> > -----Original Message-----
> > From: Gleb Natapov [mailto:gleb@redhat.com]
> > Sent: Monday, November 26, 2012 10:59 PM
> > To: Auld, Will
> > Cc: qemu-devel; mtosatti@redhat.com; kvm@vger.kernel.org; Dugger,
> > Donald D; Liu, Jinsong; Zhang, Xiantao; avi@redhat.com
> > Subject: Re: [PATCH V4 1/2] Add code to track call origin for msr
> > assignment.
> > 
> > On Mon, Nov 26, 2012 at 05:35:07PM -0800, Will Auld wrote:
> > > In order to track who initiated the call (host or guest) to modify an
> > > msr value I have changed function call parameters along the call
> > path.
> > > The specific change is to add a struct pointer parameter that points
> > > to (index, data, caller) information rather than having this
> > > information passed as individual parameters.
> > >
> > > The initial use for this capability is for updating the
> > > IA32_TSC_ADJUST msr while setting the tsc value. It is anticipated
> > > that this capability is useful other tasks.
> > >
> > > Signed-off-by: Will Auld <will.auld@intel.com>
> > > ---
> > >  arch/x86/include/asm/kvm_host.h | 12 +++++++++---
> > >  arch/x86/kvm/svm.c              | 21 +++++++++++++++------
> > >  arch/x86/kvm/vmx.c              | 24 +++++++++++++++++-------
> > >  arch/x86/kvm/x86.c              | 23 +++++++++++++++--------
> > >  arch/x86/kvm/x86.h              |  2 +-
> > >  5 files changed, 57 insertions(+), 25 deletions(-)
> > >
> > > diff --git a/arch/x86/include/asm/kvm_host.h
> > > b/arch/x86/include/asm/kvm_host.h index 09155d6..da34027 100644
> > > --- a/arch/x86/include/asm/kvm_host.h
> > > +++ b/arch/x86/include/asm/kvm_host.h
> > > @@ -598,6 +598,12 @@ struct kvm_vcpu_stat {
> > >
> > >  struct x86_instruction_info;
> > >
> > > +struct msr_data {
> > > +    bool host_initiated;
> > > +    u32 index;
> > > +    u64 data;
> > > +};
> > > +
> > >  struct kvm_x86_ops {
> > >  	int (*cpu_has_kvm_support)(void);          /* __init */
> > >  	int (*disabled_by_bios)(void);             /* __init */
> > > @@ -621,7 +627,7 @@ struct kvm_x86_ops {
> > >  	void (*set_guest_debug)(struct kvm_vcpu *vcpu,
> > >  				struct kvm_guest_debug *dbg);
> > >  	int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
> > > -	int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
> > > +	int (*set_msr)(struct kvm_vcpu *vcpu, struct msr_data *msr);
> > Emulator still calls the function pointer with msr_index & data. It
> > would be better to leave set_msr pointer as is and construct msr_data
> > emulator_set_msr() like in V3. Just drop this set_msr signature change.
> > 
> > >  	u64 (*get_segment_base)(struct kvm_vcpu *vcpu, int seg);
> > >  	void (*get_segment)(struct kvm_vcpu *vcpu,
> > >  			    struct kvm_segment *var, int seg); @@ -772,7
> > +778,7 @@ static
> > > inline int emulate_instruction(struct kvm_vcpu *vcpu,
> > >
> > >  void kvm_enable_efer_bits(u64);
> > >  int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
> > > -int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
> > > +int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
> > >
> > >  struct x86_emulate_ctxt;
> > >
> > > @@ -799,7 +805,7 @@ void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu,
> > > int *db, int *l);  int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index,
> > > u64 xcr);
> > >
> > >  int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
> > > -int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data);
> > > +int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr);
> > >
> > >  unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu);  void
> > > kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags); diff
> > > --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index
> > baead95..5ac11f0
> > > 100644
> > > --- a/arch/x86/kvm/svm.c
> > > +++ b/arch/x86/kvm/svm.c
> > > @@ -1211,6 +1211,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct
> > kvm *kvm, unsigned int id)
> > >  	struct page *msrpm_pages;
> > >  	struct page *hsave_page;
> > >  	struct page *nested_msrpm_pages;
> > > +	struct msr_data msr;
> > >  	int err;
> > >
> > >  	svm = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL); @@ -1255,7
> > > +1256,10 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm,
> > unsigned int id)
> > >  	svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
> > >  	svm->asid_generation = 0;
> > >  	init_vmcb(svm);
> > > -	kvm_write_tsc(&svm->vcpu, 0);
> > > +	msr.data = 0x0;
> > > +	msr.index = MSR_IA32_TSC;
> > > +	msr.host_initiated = true;
> > > +	kvm_write_tsc(&svm->vcpu, &msr);
> > >
> > >  	err = fx_init(&svm->vcpu);
> > >  	if (err)
> > > @@ -3147,13 +3151,15 @@ static int svm_set_vm_cr(struct kvm_vcpu
> > *vcpu, u64 data)
> > >  	return 0;
> > >  }
> > >
> > > -static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64
> > data)
> > > +static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> > >  {
> > >  	struct vcpu_svm *svm = to_svm(vcpu);
> > >
> > > +	u32 ecx = msr->index;
> > > +	u64 data = msr->data;
> > >  	switch (ecx) {
> > >  	case MSR_IA32_TSC:
> > > -		kvm_write_tsc(vcpu, data);
> > > +		kvm_write_tsc(vcpu, msr);
> > >  		break;
> > >  	case MSR_STAR:
> > >  		svm->vmcb->save.star = data;
> > > @@ -3208,20 +3214,23 @@ static int svm_set_msr(struct kvm_vcpu *vcpu,
> > unsigned ecx, u64 data)
> > >  		vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data
> > 0x%llx\n", ecx, data);
> > >  		break;
> > >  	default:
> > > -		return kvm_set_msr_common(vcpu, ecx, data);
> > > +		return kvm_set_msr_common(vcpu, msr);
> > >  	}
> > >  	return 0;
> > >  }
> > >
> > >  static int wrmsr_interception(struct vcpu_svm *svm)  {
> > > +	struct msr_data msr;
> > >  	u32 ecx = svm->vcpu.arch.regs[VCPU_REGS_RCX];
> > >  	u64 data = (svm->vcpu.arch.regs[VCPU_REGS_RAX] & -1u)
> > >  		| ((u64)(svm->vcpu.arch.regs[VCPU_REGS_RDX] & -1u) << 32);
> > >
> > > -
> > > +	msr.data = data;
> > > +	msr.index = ecx;
> > > +	msr.host_initiated = false;
> > >  	svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
> > > -	if (svm_set_msr(&svm->vcpu, ecx, data)) {
> > > +	if (svm_set_msr(&svm->vcpu, &msr)) {
> > >  		trace_kvm_msr_write_ex(ecx, data);
> > >  		kvm_inject_gp(&svm->vcpu, 0);
> > >  	} else {
> > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index
> > > c00f03d..819970f 100644
> > > --- a/arch/x86/kvm/vmx.c
> > > +++ b/arch/x86/kvm/vmx.c
> > > @@ -2197,15 +2197,17 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu,
> > u32 msr_index, u64 *pdata)
> > >   * Returns 0 on success, non-0 otherwise.
> > >   * Assumes vcpu_load() was already called.
> > >   */
> > > -static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64
> > > data)
> > > +static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data
> > > +*msr_info)
> > >  {
> > >  	struct vcpu_vmx *vmx = to_vmx(vcpu);
> > >  	struct shared_msr_entry *msr;
> > >  	int ret = 0;
> > > +	u32 msr_index = msr_info->index;
> > > +	u64 data = msr_info->data;
> > >
> > >  	switch (msr_index) {
> > >  	case MSR_EFER:
> > > -		ret = kvm_set_msr_common(vcpu, msr_index, data);
> > > +		ret = kvm_set_msr_common(vcpu, msr_info);
> > >  		break;
> > >  #ifdef CONFIG_X86_64
> > >  	case MSR_FS_BASE:
> > > @@ -2231,7 +2233,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu,
> > u32 msr_index, u64 data)
> > >  		vmcs_writel(GUEST_SYSENTER_ESP, data);
> > >  		break;
> > >  	case MSR_IA32_TSC:
> > > -		kvm_write_tsc(vcpu, data);
> > > +		kvm_write_tsc(vcpu, msr_info);
> > >  		break;
> > >  	case MSR_IA32_CR_PAT:
> > >  		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) { @@
> > -2239,7
> > > +2241,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32
> > msr_index, u64 data)
> > >  			vcpu->arch.pat = data;
> > >  			break;
> > >  		}
> > > -		ret = kvm_set_msr_common(vcpu, msr_index, data);
> > > +		ret = kvm_set_msr_common(vcpu, msr_info);
> > >  		break;
> > >  	case MSR_TSC_AUX:
> > >  		if (!vmx->rdtscp_enabled)
> > > @@ -2262,7 +2264,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu,
> > u32 msr_index, u64 data)
> > >  			}
> > >  			break;
> > >  		}
> > > -		ret = kvm_set_msr_common(vcpu, msr_index, data);
> > > +		ret = kvm_set_msr_common(vcpu, msr_info);
> > >  	}
> > >
> > >  	return ret;
> > > @@ -3835,6 +3837,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
> > >  	unsigned long a;
> > >  #endif
> > >  	int i;
> > > +	struct msr_data msr;
> > >
> > >  	/* I/O */
> > >  	vmcs_write64(IO_BITMAP_A, __pa(vmx_io_bitmap_a)); @@ -3918,7
> > > +3921,10 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
> > >  	vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL);
> > >  	set_cr4_guest_host_mask(vmx);
> > >
> > > -	kvm_write_tsc(&vmx->vcpu, 0);
> > > +	msr.data = 0x0;
> > > +	msr.index = MSR_IA32_TSC;
> > > +	msr.host_initiated = true;
> > > +	kvm_write_tsc(&vmx->vcpu, &msr);
> > >
> > >  	return 0;
> > >  }
> > > @@ -4649,11 +4655,15 @@ static int handle_rdmsr(struct kvm_vcpu
> > *vcpu)
> > >
> > >  static int handle_wrmsr(struct kvm_vcpu *vcpu)  {
> > > +	struct msr_data msr;
> > >  	u32 ecx = vcpu->arch.regs[VCPU_REGS_RCX];
> > >  	u64 data = (vcpu->arch.regs[VCPU_REGS_RAX] & -1u)
> > >  		| ((u64)(vcpu->arch.regs[VCPU_REGS_RDX] & -1u) << 32);
> > >
> > > -	if (vmx_set_msr(vcpu, ecx, data) != 0) {
> > > +	msr.data = data;
> > > +	msr.index = ecx;
> > > +	msr.host_initiated = false;
> > > +	if (vmx_set_msr(vcpu, &msr) != 0) {
> > >  		trace_kvm_msr_write_ex(ecx, data);
> > >  		kvm_inject_gp(vcpu, 0);
> > >  		return 1;
> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index
> > > 42bce48..edafa29 100644
> > > --- a/arch/x86/kvm/x86.c
> > > +++ b/arch/x86/kvm/x86.c
> > > @@ -883,9 +883,9 @@ EXPORT_SYMBOL_GPL(kvm_enable_efer_bits);
> > >   * Returns 0 on success, non-0 otherwise.
> > >   * Assumes vcpu_load() was already called.
> > >   */
> > > -int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
> > > +int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> > >  {
> > > -	return kvm_x86_ops->set_msr(vcpu, msr_index, data);
> > > +	return kvm_x86_ops->set_msr(vcpu, msr);
> > >  }
> > >
> > >  /*
> > > @@ -893,7 +893,11 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, u32
> > msr_index, u64 data)
> > >   */
> > >  static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64
> > > *data)  {
> > > -	return kvm_set_msr(vcpu, index, *data);
> > > +	struct msr_data msr;
> > > +	msr.data = *data;
> > > +	msr.index = index;
> > > +	msr.host_initiated = true;
> > > +	return kvm_set_msr(vcpu, &msr);
> > >  }
> > >
> > >  static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
> > > @@ -1043,12 +1047,13 @@ static u64 compute_guest_tsc(struct kvm_vcpu
> > *vcpu, s64 kernel_ns)
> > >  	return tsc;
> > >  }
> > >
> > > -void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
> > > +void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
> > >  {
> > >  	struct kvm *kvm = vcpu->kvm;
> > >  	u64 offset, ns, elapsed;
> > >  	unsigned long flags;
> > >  	s64 usdiff;
> > > +	u64 data = msr->data;
> > >
> > >  	raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
> > >  	offset = kvm_x86_ops->compute_tsc_offset(vcpu, data); @@ -1561,9
> > > +1566,11 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
> > >  		&vcpu->arch.st.steal, sizeof(struct kvm_steal_time));  }
> > >
> > > -int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> > > +int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data
> > > +*msr_info)
> > >  {
> > >  	bool pr = false;
> > > +	u32 msr = msr_info->index;
> > > +	u64 data = msr_info->data;
> > >
> > >  	switch (msr) {
> > >  	case MSR_EFER:
> > > @@ -4283,10 +4290,10 @@ static int emulator_get_msr(struct
> > x86_emulate_ctxt *ctxt,
> > >  	return kvm_get_msr(emul_to_vcpu(ctxt), msr_index, pdata);  }
> > >
> > > -static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
> > > -			    u32 msr_index, u64 data)
> > > +static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
> > > +				struct msr_data * msr)
> > >  {
> > > -	return kvm_set_msr(emul_to_vcpu(ctxt), msr_index, data);
> > > +	return kvm_set_msr(emul_to_vcpu(ctxt), msr);
> > >  }
> > >
> > >  static int emulator_read_pmc(struct x86_emulate_ctxt *ctxt, diff
> > > --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index
> > 3d1134d..1dcb8e3
> > > 100644
> > > --- a/arch/x86/kvm/x86.h
> > > +++ b/arch/x86/kvm/x86.h
> > > @@ -112,7 +112,7 @@ void kvm_before_handle_nmi(struct kvm_vcpu
> > *vcpu);
> > > void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);  int
> > > kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int
> > > inc_eip);
> > >
> > > -void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data);
> > > +void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr);
> > >
> > >  int kvm_read_guest_virt(struct x86_emulate_ctxt *ctxt,
> > >  	gva_t addr, void *val, unsigned int bytes,
> > > --
> > > 1.8.0.rc0
> > >
> > >
> > >
> > 
> > --
> > 			Gleb.

--
			Gleb.