[PATCH v3 6/9] x86/HVM: convert hvm_virtual_to_linear_addr() to be remote-capable

[Jan Beulich <jbeulich@xxxxxxxx>]

While all present callers want to act on "current", stack dumping for
HVM vCPU-s will require the function to be able to act on a remote vCPU.
To avoid touching all present callers, convert the existing function to
an inline wrapper around the extend new one.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Alternatively the actual dumping patch could avoid using this more
elaborate function and, ignoring access checks, simply add in the SS
segment base itself (if needed in the first place).
---
v3: New.

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2526,7 +2526,8 @@ int hvm_set_cr4(unsigned long value, boo
     return X86EMUL_OKAY;
 }
 
-bool_t hvm_virtual_to_linear_addr(
+bool hvm_vcpu_virtual_to_linear(
+    struct vcpu *v,
     enum x86_segment seg,
     const struct segment_register *reg,
     unsigned long offset,
@@ -2535,8 +2536,9 @@ bool_t hvm_virtual_to_linear_addr(
     const struct segment_register *active_cs,
     unsigned long *linear_addr)
 {
-    const struct vcpu *curr = current;
     unsigned long addr = offset, last_byte;
+    const struct cpu_user_regs *regs = v == current ? guest_cpu_user_regs()
+                                                    : &v->arch.user_regs;
     bool_t okay = 0;
 
     /*
@@ -2547,7 +2549,7 @@ bool_t hvm_virtual_to_linear_addr(
      */
     ASSERT(seg < x86_seg_none);
 
-    if ( !(curr->arch.hvm.guest_cr[0] & X86_CR0_PE) )
+    if ( !(v->arch.hvm.guest_cr[0] & X86_CR0_PE) )
     {
         /*
          * REAL MODE: Don't bother with segment access checks.
@@ -2555,7 +2557,7 @@ bool_t hvm_virtual_to_linear_addr(
          */
         addr = (uint32_t)(addr + reg->base);
     }
-    else if ( (guest_cpu_user_regs()->eflags & X86_EFLAGS_VM) &&
+    else if ( (regs->eflags & X86_EFLAGS_VM) &&
               is_x86_user_segment(seg) )
     {
         /* VM86 MODE: Fixed 64k limits on all user segments. */
@@ -2564,7 +2566,7 @@ bool_t hvm_virtual_to_linear_addr(
         if ( max(offset, last_byte) >> 16 )
             goto out;
     }
-    else if ( hvm_long_mode_active(curr) &&
+    else if ( hvm_long_mode_active(v) &&
               (is_x86_system_segment(seg) || active_cs->l) )
     {
         /*
@@ -2636,7 +2638,7 @@ bool_t hvm_virtual_to_linear_addr(
         else if ( last_byte > reg->limit )
             goto out; /* last byte is beyond limit */
         else if ( last_byte < offset &&
-                  curr->domain->arch.cpuid->x86_vendor == X86_VENDOR_AMD )
+                  v->domain->arch.cpuid->x86_vendor == X86_VENDOR_AMD )
             goto out; /* access wraps */
     }
 
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -314,7 +314,9 @@ enum hvm_access_type {
     hvm_access_read,
     hvm_access_write
 };
-bool_t hvm_virtual_to_linear_addr(
+
+bool hvm_vcpu_virtual_to_linear(
+    struct vcpu *v,
     enum x86_segment seg,
     const struct segment_register *reg,
     unsigned long offset,
@@ -323,6 +325,19 @@ bool_t hvm_virtual_to_linear_addr(
     const struct segment_register *active_cs,
     unsigned long *linear_addr);
 
+static inline bool hvm_virtual_to_linear_addr(
+    enum x86_segment seg,
+    const struct segment_register *reg,
+    unsigned long offset,
+    unsigned int bytes,
+    enum hvm_access_type access_type,
+    const struct segment_register *active_cs,
+    unsigned long *linear)
+{
+    return hvm_vcpu_virtual_to_linear(current, seg, reg, offset, bytes,
+                                      access_type, active_cs, linear);
+}
+
 void *hvm_map_guest_frame_rw(unsigned long gfn, bool_t permanent,
                              bool_t *writable);
 void *hvm_map_guest_frame_ro(unsigned long gfn, bool_t permanent);