[PATCH] x86/domain: Drop the only-written smap_check_policy infrastructure

* [PATCH] x86/domain: Drop the only-written smap_check_policy infrastructure
@ 2018-05-08 13:03 Andrew Cooper
  2018-05-08 16:05 ` George Dunlap
  2018-05-08 16:10 ` Roger Pau Monné
  0 siblings, 2 replies; 7+ messages in thread
From: Andrew Cooper @ 2018-05-08 13:03 UTC (permalink / raw)
  To: Xen-devel
  Cc: Juergen Gross, Wei Liu, Jason Andryuk, Andrew Cooper, Jan Beulich,
	Roger Pau Monné

c/s 4c5d78a10d "x86/pagewalk: Re-implement the pagetable walker" dropped the
consumer of smap_policy.  Looking at c/s 31ae587e6f which introduced the
smap_check logic, it exists only to work around a bug in guest_walk_tables()
was resolved by the aformentioned commit.

Remove the unused variables and associated infrastructure.

Reported-by: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Juergen Gross <jgross@suse.com>
CC: Jason Andryuk <jandryuk@gmail.com>

I'm on the fence as to whether to suggest this for 4.11 at this point.  Its
probably not something to be backported, but it is a nice bit of cleanup, and
removes a particularly gross hack.
---
 xen/arch/x86/domain.c        |  7 +------
 xen/arch/x86/time.c          |  3 +--
 xen/include/asm-x86/domain.h | 13 -------------
 3 files changed, 2 insertions(+), 21 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 801ac33..4ff3d2f3 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -217,13 +217,9 @@ void dump_pageframe_info(struct domain *d)
 void update_guest_memory_policy(struct vcpu *v,
                                 struct guest_memory_policy *policy)
 {
-    smap_check_policy_t old_smap_policy = v->arch.smap_check_policy;
     bool old_guest_mode = nestedhvm_is_n2(v);
     bool new_guest_mode = policy->nested_guest_mode;
 
-    v->arch.smap_check_policy = policy->smap_policy;
-    policy->smap_policy = old_smap_policy;
-
     /*
      * When 'v' is in the nested guest mode, all guest copy
      * functions/macros which finally call paging_gva_to_gfn()
@@ -1541,8 +1537,7 @@ void paravirt_ctxt_switch_to(struct vcpu *v)
 bool update_runstate_area(struct vcpu *v)
 {
     bool rc;
-    struct guest_memory_policy policy =
-        { .smap_policy = SMAP_CHECK_ENABLED, .nested_guest_mode = false };
+    struct guest_memory_policy policy = { .nested_guest_mode = false };
     void __user *guest_handle = NULL;
 
     if ( guest_handle_is_null(runstate_guest(v)) )
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 84c1c0c..c342d00 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -1106,8 +1106,7 @@ bool update_secondary_system_time(struct vcpu *v,
                                   struct vcpu_time_info *u)
 {
     XEN_GUEST_HANDLE(vcpu_time_info_t) user_u = v->arch.time_info_guest;
-    struct guest_memory_policy policy =
-        { .smap_policy = SMAP_CHECK_ENABLED, .nested_guest_mode = false };
+    struct guest_memory_policy policy = { .nested_guest_mode = false };
 
     if ( guest_handle_is_null(user_u) )
         return true;
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index 8b66096..197f8d6 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -508,12 +508,6 @@ struct pv_vcpu
     struct vcpu_time_info pending_system_time;
 };
 
-typedef enum __packed {
-    SMAP_CHECK_HONOR_CPL_AC,    /* honor the guest's CPL and AC */
-    SMAP_CHECK_ENABLED,         /* enable the check */
-    SMAP_CHECK_DISABLED,        /* disable the check */
-} smap_check_policy_t;
-
 struct arch_vcpu
 {
     /*
@@ -569,12 +563,6 @@ struct arch_vcpu
      * and thus should be saved/restored. */
     bool_t nonlazy_xstate_used;
 
-    /*
-     * The SMAP check policy when updating runstate_guest(v) and the
-     * secondary system time.
-     */
-    smap_check_policy_t smap_check_policy;
-
     struct vmce vmce;
 
     struct paging_vcpu paging;
@@ -595,7 +583,6 @@ struct arch_vcpu
 
 struct guest_memory_policy
 {
-    smap_check_policy_t smap_policy;
     bool nested_guest_mode;
 };
 
-- 
2.1.4


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