Re: [Xen-devel] [PATCH v4 02/12] x86/HVM: patch indirect calls through hvm_funcs to direct ones
>>> On 03.10.18 at 20:55, wrote:
> On 02/10/18 11:12, Jan Beulich wrote:
>> This is intentionally not touching hooks used rarely (or not at all)
>> during the lifetime of a VM, like {domain,vcpu}_initialise or cpu_up,
>> as well as nested, VM event, and altp2m ones (they can all be done
>> later, if so desired). Virtual Interrupt delivery ones will be dealt
>> with in a subsequent patch.
>>
>> Signed-off-by: Jan Beulich
>> Reviewed-by: Wei Liu
>
> Acked-by: Andrew Cooper
Thanks.
> It is a shame that we don't have a variation such as cond_alt_vcall()
> which nops out the entire call when the function pointer is NULL, but I
> can't think of any sane way of trying to make that happen.
I think this could be made work, e.g. by further utilizing special values
of the displacement of the CALL insn (out of the non-sensible ones we
currently use only -5; arguably using -4 ... -1 would be liable to
conflict with not entirely dumb disassemblers, which may imply an
instruction boundary at the target of any CALL/JMP without special
casing such bogus values).
If we thought this was a worthwhile avenue to explore, non-void
calls could be patched this way too, as long as the replacement
"return" value is a compile time constant (i.e. we'd have a compile
time "MOV $, %eax" to patch in). We'd merely have to
sort out where to place this alternative replacement code.
Jan
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Re: [Xen-devel] [PATCH v4 02/12] x86/HVM: patch indirect calls through hvm_funcs to direct ones
> -Original Message-
> From: Jan Beulich [mailto:jbeul...@suse.com]
> Sent: 02 October 2018 11:13
> To: xen-devel
> Cc: Andrew Cooper ; Paul Durrant
> ; Wei Liu
> Subject: [PATCH v4 02/12] x86/HVM: patch indirect calls through hvm_funcs
> to direct ones
>
> This is intentionally not touching hooks used rarely (or not at all)
> during the lifetime of a VM, like {domain,vcpu}_initialise or cpu_up,
> as well as nested, VM event, and altp2m ones (they can all be done
> later, if so desired). Virtual Interrupt delivery ones will be dealt
> with in a subsequent patch.
>
> Signed-off-by: Jan Beulich
Reviewed-by: Paul Durrant
> Reviewed-by: Wei Liu
> ---
> v3: Re-base.
> v2: Drop open-coded numbers from macro invocations. Re-base.
>
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -2104,7 +2104,7 @@ static int hvmemul_write_msr(
> static int hvmemul_wbinvd(
> struct x86_emulate_ctxt *ctxt)
> {
> -hvm_funcs.wbinvd_intercept();
> +alternative_vcall(hvm_funcs.wbinvd_intercept);
> return X86EMUL_OKAY;
> }
>
> @@ -2122,7 +2122,7 @@ static int hvmemul_get_fpu(
> struct vcpu *curr = current;
>
> if ( !curr->fpu_dirtied )
> -hvm_funcs.fpu_dirty_intercept();
> +alternative_vcall(hvm_funcs.fpu_dirty_intercept);
> else if ( type == X86EMUL_FPU_fpu )
> {
> const typeof(curr->arch.xsave_area->fpu_sse) *fpu_ctxt =
> @@ -2239,7 +2239,7 @@ static void hvmemul_put_fpu(
> {
> curr->fpu_dirtied = false;
> stts();
> -hvm_funcs.fpu_leave(curr);
> +alternative_vcall(hvm_funcs.fpu_leave, curr);
> }
> }
> }
> @@ -2401,7 +2401,8 @@ static int _hvm_emulate_one(struct hvm_e
> if ( hvmemul_ctxt->intr_shadow != new_intr_shadow )
> {
> hvmemul_ctxt->intr_shadow = new_intr_shadow;
> -hvm_funcs.set_interrupt_shadow(curr, new_intr_shadow);
> +alternative_vcall(hvm_funcs.set_interrupt_shadow,
> + curr, new_intr_shadow);
> }
>
> if ( hvmemul_ctxt->ctxt.retire.hlt &&
> @@ -2538,7 +2539,8 @@ void hvm_emulate_init_once(
>
> memset(hvmemul_ctxt, 0, sizeof(*hvmemul_ctxt));
>
> -hvmemul_ctxt->intr_shadow = hvm_funcs.get_interrupt_shadow(curr);
> +hvmemul_ctxt->intr_shadow =
> +alternative_call(hvm_funcs.get_interrupt_shadow, curr);
> hvmemul_get_seg_reg(x86_seg_cs, hvmemul_ctxt);
> hvmemul_get_seg_reg(x86_seg_ss, hvmemul_ctxt);
>
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -272,12 +272,12 @@ void hvm_set_rdtsc_exiting(struct domain
> struct vcpu *v;
>
> for_each_vcpu ( d, v )
> -hvm_funcs.set_rdtsc_exiting(v, enable);
> +alternative_vcall(hvm_funcs.set_rdtsc_exiting, v, enable);
> }
>
> void hvm_get_guest_pat(struct vcpu *v, u64 *guest_pat)
> {
> -if ( !hvm_funcs.get_guest_pat(v, guest_pat) )
> +if ( !alternative_call(hvm_funcs.get_guest_pat, v, guest_pat) )
> *guest_pat = v->arch.hvm.pat_cr;
> }
>
> @@ -302,7 +302,7 @@ int hvm_set_guest_pat(struct vcpu *v, u6
> return 0;
> }
>
> -if ( !hvm_funcs.set_guest_pat(v, guest_pat) )
> +if ( !alternative_call(hvm_funcs.set_guest_pat, v, guest_pat) )
> v->arch.hvm.pat_cr = guest_pat;
>
> return 1;
> @@ -342,7 +342,7 @@ bool hvm_set_guest_bndcfgs(struct vcpu *
> /* nothing, best effort only */;
> }
>
> -return hvm_funcs.set_guest_bndcfgs(v, val);
> +return alternative_call(hvm_funcs.set_guest_bndcfgs, v, val);
> }
>
> /*
> @@ -500,7 +500,8 @@ void hvm_migrate_pirqs(struct vcpu *v)
> static bool hvm_get_pending_event(struct vcpu *v, struct x86_event *info)
> {
> info->cr2 = v->arch.hvm.guest_cr[2];
> -return hvm_funcs.get_pending_event(v, info);
> +
> +return alternative_call(hvm_funcs.get_pending_event, v, info);
> }
>
> void hvm_do_resume(struct vcpu *v)
> @@ -1651,7 +1652,7 @@ void hvm_inject_event(const struct x86_e
> }
> }
>
> -hvm_funcs.inject_event(event);
> +alternative_vcall(hvm_funcs.inject_event, event);
> }
>
> int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
> @@ -2238,7 +2239,7 @@ int hvm_set_cr0(unsigned long value, boo
> (!rangeset_is_empty(d->iomem_caps) ||
>!rangeset_is_empty(d->arch.ioport_caps) ||
>has_arch_pdevs(d)) )
> -hvm_funcs.handle_cd(v, value);
> +alternative_vcall(hvm_funcs.handle_cd, v, value);
>
> hvm_update_cr(v, 0, value);
>
> @@ -3477,7 +3478,8 @@ int hvm_msr_read_intercept(unsigned int
> goto gp_fault;
> /* If ret == 0 then this is not an MCE MSR, see other MSRs. */
> ret = ((ret == 0)
> - ? hvm_funcs.msr_read_intercept(msr, msr_content)
> + ? alternative_call(hvm_funcs.msr_read_intercept,
> + msr, msr_content)
> : X86EMUL_OKAY);
[Xen-devel] [PATCH v4 02/12] x86/HVM: patch indirect calls through hvm_funcs to direct ones
This is intentionally not touching hooks used rarely (or not at all)
during the lifetime of a VM, like {domain,vcpu}_initialise or cpu_up,
as well as nested, VM event, and altp2m ones (they can all be done
later, if so desired). Virtual Interrupt delivery ones will be dealt
with in a subsequent patch.
Signed-off-by: Jan Beulich
Reviewed-by: Wei Liu
---
v3: Re-base.
v2: Drop open-coded numbers from macro invocations. Re-base.
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2104,7 +2104,7 @@ static int hvmemul_write_msr(
static int hvmemul_wbinvd(
struct x86_emulate_ctxt *ctxt)
{
-hvm_funcs.wbinvd_intercept();
+alternative_vcall(hvm_funcs.wbinvd_intercept);
return X86EMUL_OKAY;
}
@@ -2122,7 +2122,7 @@ static int hvmemul_get_fpu(
struct vcpu *curr = current;
if ( !curr->fpu_dirtied )
-hvm_funcs.fpu_dirty_intercept();
+alternative_vcall(hvm_funcs.fpu_dirty_intercept);
else if ( type == X86EMUL_FPU_fpu )
{
const typeof(curr->arch.xsave_area->fpu_sse) *fpu_ctxt =
@@ -2239,7 +2239,7 @@ static void hvmemul_put_fpu(
{
curr->fpu_dirtied = false;
stts();
-hvm_funcs.fpu_leave(curr);
+alternative_vcall(hvm_funcs.fpu_leave, curr);
}
}
}
@@ -2401,7 +2401,8 @@ static int _hvm_emulate_one(struct hvm_e
if ( hvmemul_ctxt->intr_shadow != new_intr_shadow )
{
hvmemul_ctxt->intr_shadow = new_intr_shadow;
-hvm_funcs.set_interrupt_shadow(curr, new_intr_shadow);
+alternative_vcall(hvm_funcs.set_interrupt_shadow,
+ curr, new_intr_shadow);
}
if ( hvmemul_ctxt->ctxt.retire.hlt &&
@@ -2538,7 +2539,8 @@ void hvm_emulate_init_once(
memset(hvmemul_ctxt, 0, sizeof(*hvmemul_ctxt));
-hvmemul_ctxt->intr_shadow = hvm_funcs.get_interrupt_shadow(curr);
+hvmemul_ctxt->intr_shadow =
+alternative_call(hvm_funcs.get_interrupt_shadow, curr);
hvmemul_get_seg_reg(x86_seg_cs, hvmemul_ctxt);
hvmemul_get_seg_reg(x86_seg_ss, hvmemul_ctxt);
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -272,12 +272,12 @@ void hvm_set_rdtsc_exiting(struct domain
struct vcpu *v;
for_each_vcpu ( d, v )
-hvm_funcs.set_rdtsc_exiting(v, enable);
+alternative_vcall(hvm_funcs.set_rdtsc_exiting, v, enable);
}
void hvm_get_guest_pat(struct vcpu *v, u64 *guest_pat)
{
-if ( !hvm_funcs.get_guest_pat(v, guest_pat) )
+if ( !alternative_call(hvm_funcs.get_guest_pat, v, guest_pat) )
*guest_pat = v->arch.hvm.pat_cr;
}
@@ -302,7 +302,7 @@ int hvm_set_guest_pat(struct vcpu *v, u6
return 0;
}
-if ( !hvm_funcs.set_guest_pat(v, guest_pat) )
+if ( !alternative_call(hvm_funcs.set_guest_pat, v, guest_pat) )
v->arch.hvm.pat_cr = guest_pat;
return 1;
@@ -342,7 +342,7 @@ bool hvm_set_guest_bndcfgs(struct vcpu *
/* nothing, best effort only */;
}
-return hvm_funcs.set_guest_bndcfgs(v, val);
+return alternative_call(hvm_funcs.set_guest_bndcfgs, v, val);
}
/*
@@ -500,7 +500,8 @@ void hvm_migrate_pirqs(struct vcpu *v)
static bool hvm_get_pending_event(struct vcpu *v, struct x86_event *info)
{
info->cr2 = v->arch.hvm.guest_cr[2];
-return hvm_funcs.get_pending_event(v, info);
+
+return alternative_call(hvm_funcs.get_pending_event, v, info);
}
void hvm_do_resume(struct vcpu *v)
@@ -1651,7 +1652,7 @@ void hvm_inject_event(const struct x86_e
}
}
-hvm_funcs.inject_event(event);
+alternative_vcall(hvm_funcs.inject_event, event);
}
int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
@@ -2238,7 +2239,7 @@ int hvm_set_cr0(unsigned long value, boo
(!rangeset_is_empty(d->iomem_caps) ||
!rangeset_is_empty(d->arch.ioport_caps) ||
has_arch_pdevs(d)) )
-hvm_funcs.handle_cd(v, value);
+alternative_vcall(hvm_funcs.handle_cd, v, value);
hvm_update_cr(v, 0, value);
@@ -3477,7 +3478,8 @@ int hvm_msr_read_intercept(unsigned int
goto gp_fault;
/* If ret == 0 then this is not an MCE MSR, see other MSRs. */
ret = ((ret == 0)
- ? hvm_funcs.msr_read_intercept(msr, msr_content)
+ ? alternative_call(hvm_funcs.msr_read_intercept,
+ msr, msr_content)
: X86EMUL_OKAY);
break;
}
@@ -3637,7 +3639,8 @@ int hvm_msr_write_intercept(unsigned int
goto gp_fault;
/* If ret == 0 then this is not an MCE MSR, see other MSRs. */
ret = ((ret == 0)
- ? hvm_funcs.msr_write_intercept(msr, msr_content)
+ ? alternative_call(hvm_funcs.msr_write_intercept,
+ msr, msr_content)
: X86EMUL_OKAY);
break;
}
@@ -3829,7 +3832,7 @@ void hvm_hypercall_page_initialise(struc
