[Xen-devel] [PATCH RFC] pvh: clearly specify used parameters in vcpu_guest_context

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

The aim of this patch is to define a stable way in which PVH is
going to do AP bringup.

Since we are running inside of a HVM container, PVH should only need
to set flags, cr3 and user_regs in order to bring up a vCPU, the rest
can be set once the vCPU is started using the bare metal methods.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
---
 xen/arch/x86/domain.c             |   11 +++--------
 xen/arch/x86/hvm/vmx/vmx.c        |    4 ----
 xen/include/public/arch-x86/xen.h |    6 ++----
 3 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index a3868f9..b643eaf 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -704,9 +704,11 @@ int arch_set_info_guest(
         /* PVH 32bitfixme */
         ASSERT(!compat);
 
-        if ( c(ctrlreg[1]) || c(ldt_base) || c(ldt_ents) ||
+        if ( c(ctrlreg[0]) || c(ctrlreg[1]) || c(ctrlreg[2]) ||
+             c(ctrlreg[4]) || c(ldt_base) || c(ldt_ents) ||
              c(user_regs.cs) || c(user_regs.ss) || c(user_regs.es) ||
              c(user_regs.ds) || c(user_regs.fs) || c(user_regs.gs) ||
+             c(kernel_ss) || c(kernel_sp) || c.nat->gs_base_kernel ||
              c.nat->gdt_ents || c.nat->fs_base || c.nat->gs_base_user )
             return -EINVAL;
     }
@@ -745,13 +747,6 @@ int arch_set_info_guest(
 
     if ( has_hvm_container_vcpu(v) )
     {
-        /*
-         * NB: TF_kernel_mode is set unconditionally for HVM guests,
-         * so we always use the gs_base_kernel here. If we change this
-         * function to imitate the PV functionality, we'll need to
-         * make it pay attention to the kernel bit.
-         */
-        hvm_set_info_guest(v, compat ? 0 : c.nat->gs_base_kernel);
 
         if ( is_hvm_vcpu(v) || v->is_initialised )
             goto out;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index f0132a4..90999ca 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1492,10 +1492,6 @@ static void vmx_set_info_guest(struct vcpu *v, uint64_t 
gs_base_kernel)
         __vmwrite(GUEST_INTERRUPTIBILITY_INFO, intr_shadow);
     }
 
-    /* PVH 32bitfixme */
-    if ( is_pvh_vcpu(v) )
-        __vmwrite(GUEST_GS_BASE, gs_base_kernel);
-
     vmx_vmcs_exit(v);
 }
 
diff --git a/xen/include/public/arch-x86/xen.h 
b/xen/include/public/arch-x86/xen.h
index 5d220ce..46736ae 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -161,10 +161,8 @@ typedef uint64_t tsc_timestamp_t; /* RDTSC timestamp */
  * - For HVM guests, the structures read include: fpu_ctxt (if
  * VGCT_I387_VALID is set), flags, user_regs, debugreg[*]
  *
- * - PVH guests are the same as HVM guests, but additionally set cr3,
- * and for 64-bit guests, gs_base_kernel.  Additionally, the following
- * entries must be 0: ctrlreg[1], ldt_base, ldt_ents, user_regs.{cs,
- * ss, es, ds, fs, gs), gdt_ents, fs_base, and gs_base_user.
+ * - PVH guests are the same as HVM guests, but additionally use ctrlreg[3] to
+ * set cr3. All other unused fields must be set to 0.
  */
 struct vcpu_guest_context {
     /* FPU registers come first so they can be aligned for FXSAVE/FXRSTOR. */
-- 
1.7.7.5 (Apple Git-26)


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