Re: [PATCH v2 6/8] x86/iommu: call pi_update_irte through an hvm_function callback

[Xenia Ragiadakou]

On 1/12/23 14:16, Jan Beulich wrote:

On 04.01.2023 09:45, Xenia Ragiadakou wrote:

--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2143,6 +2143,14 @@ static bool cf_check vmx_test_pir(const struct vcpu *v, 
uint8_t vec)
      return pi_test_pir(vec, &v->arch.hvm.vmx.pi_desc);
  }

+static int cf_check vmx_pi_update_irte(const struct vcpu *v,

+                                       const struct pirq *pirq, uint8_t gvec)
+{
+    const struct pi_desc *pi_desc = v ? &v->arch.hvm.vmx.pi_desc : NULL;
+
+    return pi_update_irte(pi_desc, pirq, gvec);
+}

This being the only caller of pi_update_irte(), I don't see the point in
having the extra wrapper. Adjust pi_update_irte() such that it can be
used as the intended hook directly. Plus perhaps prefix it with vtd_.

Ok I will remove the extra wrapper.

@@ -2591,6 +2599,8 @@ static struct hvm_function_table __initdata_cf_clobber 
vmx_function_table = {
      .tsc_scaling = {
          .max_ratio = VMX_TSC_MULTIPLIER_MAX,
      },
+
+    .pi_update_irte = vmx_pi_update_irte,

You want to install this hook only when iommu_intpost (i.e. the only case
when it can actually be called, and only when INTEL_IOMMU=y (avoiding the
need for an inline stub of pi_update_irte() or whatever its final name is
going to be.

Ok will do.

@@ -250,6 +252,9 @@ struct hvm_function_table {
          /* Architecture function to setup TSC scaling ratio */
          void (*setup)(struct vcpu *v);
      } tsc_scaling;
+
+    int (*pi_update_irte)(const struct vcpu *v,
+                          const struct pirq *pirq, uint8_t gvec);
  };

Please can this be moved higher up, e.g. next to .

Right after handle_eoi would be ok? or higher up?

@@ -774,6 +779,16 @@ static inline void hvm_set_nonreg_state(struct vcpu *v,
          alternative_vcall(hvm_funcs.set_nonreg_state, v, nrs);
  }

+static inline int hvm_pi_update_irte(const struct vcpu *v,

+                                     const struct pirq *pirq, uint8_t gvec)
+{
+    if ( hvm_funcs.pi_update_irte )
+        return alternative_call(hvm_funcs.pi_update_irte, v, pirq, gvec);
+
+    return -EOPNOTSUPP;

I don't think the conditional is needed, at least not with the other
suggested adjustments. Plus the way alternative patching works, a NULL
hook will be converted to some equivalent of BUG() anyway, so
ASSERT_UNREACHABLE() should also be unnecessary.

Ok will remove it.

+}
+
+
  #else  /* CONFIG_HVM */

Please don't add double blank lines.

Ok will fix.

--- a/xen/arch/x86/include/asm/hvm/vmx/vmx.h
+++ b/xen/arch/x86/include/asm/hvm/vmx/vmx.h
@@ -146,6 +146,17 @@ static inline void pi_clear_sn(struct pi_desc *pi_desc)
      clear_bit(POSTED_INTR_SN, &pi_desc->control);
  }

+#ifdef CONFIG_INTEL_IOMMU

+int pi_update_irte(const struct pi_desc *pi_desc,
+                   const struct pirq *pirq, const uint8_t gvec);
+#else
+static inline int pi_update_irte(const struct pi_desc *pi_desc,
+                                 const struct pirq *pirq, const uint8_t gvec)
+{
+    return -EOPNOTSUPP;
+}
+#endif

This still is a VT-d function, so I think its declaration would better
remain in asm/iommu.h.

Jan

--
Xenia