[Xen-devel] [PATCH 2/5] hvm/mtrr: use the hardware number of variable ranges for Dom0

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Expand the size of the variable ranges array to match the size of the
underlying hardware, this is a preparatory change for copying the
hardware MTRR state for Dom0.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/mtrr.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
index b3c08c3977..95a3deabea 100644
--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -154,14 +154,17 @@ uint8_t pat_type_2_pte_flags(uint8_t pat_type)
 int hvm_vcpu_cacheattr_init(struct vcpu *v)
 {
     struct mtrr_state *m = &v->arch.hvm_vcpu.mtrr;
+    unsigned int num_var_ranges =
+        is_hardware_domain(v->domain) ? (mtrr_state.mtrr_cap & 0xff)
+                                      : MTRR_VCNT;
 
     memset(m, 0, sizeof(*m));
 
-    m->var_ranges = xzalloc_array(struct mtrr_var_range, MTRR_VCNT);
+    m->var_ranges = xzalloc_array(struct mtrr_var_range, num_var_ranges);
     if ( m->var_ranges == NULL )
         return -ENOMEM;
 
-    m->mtrr_cap = (1u << 10) | (1u << 8) | MTRR_VCNT;
+    m->mtrr_cap = (1u << 10) | (1u << 8) | num_var_ranges;
 
     v->arch.hvm_vcpu.pat_cr =
         ((uint64_t)PAT_TYPE_WRBACK) |               /* PAT0: WB */
@@ -683,6 +686,9 @@ static int hvm_save_mtrr_msr(struct domain *d, 
hvm_domain_context_t *h)
                                 | (mtrr_state->enabled << 10);
         hw_mtrr.msr_mtrr_cap = mtrr_state->mtrr_cap;
 
+        if ( (mtrr_state->mtrr_cap & 0xff) != MTRR_VCNT )
+            return -EINVAL;
+
         for ( i = 0; i < MTRR_VCNT; i++ )
         {
             /* save physbase */
@@ -727,6 +733,9 @@ static int hvm_load_mtrr_msr(struct domain *d, 
hvm_domain_context_t *h)
 
     mtrr_state->mtrr_cap = hw_mtrr.msr_mtrr_cap;
 
+    if ( (mtrr_state->mtrr_cap & 0xff) != MTRR_VCNT )
+        return -EINVAL;
+
     for ( i = 0; i < NUM_FIXED_MSR; i++ )
         mtrr_fix_range_msr_set(d, mtrr_state, i, hw_mtrr.msr_mtrr_fixed[i]);
 
-- 
2.17.0


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