Xen 4.16.4-pre-patchset-04.16.4-pre-patchset-0

Signed-off-by: Tomáš Mózes <hydrapolic@gmail.com>

1 files changed, 129 insertions, 0 deletions

diff --git a/0043-x86-altp2m-help-gcc13-to-avoid-it-emitting-a-warning.patch b/0043-x86-altp2m-help-gcc13-to-avoid-it-emitting-a-warning.patch
new file mode 100644
index 0000000..0e040ad
--- /dev/null
+++ b/0043-x86-altp2m-help-gcc13-to-avoid-it-emitting-a-warning.patch
@@ -0,0 +1,129 @@
+From cdde3171a2a932a6836b094c4387412e27414ec9 Mon Sep 17 00:00:00 2001
+From: Jan Beulich <jbeulich@suse.com>
+Date: Tue, 21 Mar 2023 13:51:42 +0100
+Subject: [PATCH 43/61] x86/altp2m: help gcc13 to avoid it emitting a warning
+
+Switches of altp2m-s always expect a valid altp2m to be in place (and
+indeed altp2m_vcpu_initialise() sets the active one to be at index 0).
+The compiler, however, cannot know that, and hence it cannot eliminate
+p2m_get_altp2m()'s case of returnin (literal) NULL. If then the compiler
+decides to special case that code path in the caller, the dereference in
+instances of
+
+    atomic_dec(&p2m_get_altp2m(v)->active_vcpus);
+
+can, to the code generator, appear to be NULL dereferences, leading to
+
+In function 'atomic_dec',
+    inlined from '...' at ...:
+./arch/x86/include/asm/atomic.h:182:5: error: array subscript 0 is outside array bounds of 'int[0]' [-Werror=array-bounds=]
+
+Aid the compiler by adding a BUG_ON() checking the return value of the
+problematic p2m_get_altp2m(). Since with the use of the local variable
+the 2nd p2m_get_altp2m() each will look questionable at the first glance
+(Why is the local variable not used here?), open-code the only relevant
+piece of p2m_get_altp2m() there.
+
+To avoid repeatedly doing these transformations, and also to limit how
+"bad" the open-coding really is, convert the entire operation to an
+inline helper, used by all three instances (and accepting the redundant
+BUG_ON(idx >= MAX_ALTP2M) in two of the three cases).
+
+Reported-by: Charles Arnold <carnold@suse.com>
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
+master commit: be62b1fc2aa7375d553603fca07299da765a89fe
+master date: 2023-03-13 15:16:21 +0100
+---
+ xen/arch/x86/hvm/vmx/vmx.c |  8 +-------
+ xen/arch/x86/mm/p2m.c      | 14 ++------------
+ xen/include/asm-x86/p2m.h  | 20 ++++++++++++++++++++
+ 3 files changed, 23 insertions(+), 19 deletions(-)
+
+diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
+index 094141be9a..c8a839cd5e 100644
+--- a/xen/arch/x86/hvm/vmx/vmx.c
++++ b/xen/arch/x86/hvm/vmx/vmx.c
+@@ -4036,13 +4036,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
+             }
+         }
+ 
+-        if ( idx != vcpu_altp2m(v).p2midx )
+-        {
+-            BUG_ON(idx >= MAX_ALTP2M);
+-            atomic_dec(&p2m_get_altp2m(v)->active_vcpus);
+-            vcpu_altp2m(v).p2midx = idx;
+-            atomic_inc(&p2m_get_altp2m(v)->active_vcpus);
+-        }
++        p2m_set_altp2m(v, idx);
+     }
+ 
+     /* XXX: This looks ugly, but we need a mechanism to ensure
+diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
+index 8781df9dda..2d41446a69 100644
+--- a/xen/arch/x86/mm/p2m.c
++++ b/xen/arch/x86/mm/p2m.c
+@@ -2194,13 +2194,8 @@ bool_t p2m_switch_vcpu_altp2m_by_id(struct vcpu *v, unsigned int idx)
+ 
+     if ( d->arch.altp2m_eptp[idx] != mfn_x(INVALID_MFN) )
+     {
+-        if ( idx != vcpu_altp2m(v).p2midx )
+-        {
+-            atomic_dec(&p2m_get_altp2m(v)->active_vcpus);
+-            vcpu_altp2m(v).p2midx = idx;
+-            atomic_inc(&p2m_get_altp2m(v)->active_vcpus);
++        if ( p2m_set_altp2m(v, idx) )
+             altp2m_vcpu_update_p2m(v);
+-        }
+         rc = 1;
+     }
+ 
+@@ -2471,13 +2466,8 @@ int p2m_switch_domain_altp2m_by_id(struct domain *d, unsigned int idx)
+     if ( d->arch.altp2m_visible_eptp[idx] != mfn_x(INVALID_MFN) )
+     {
+         for_each_vcpu( d, v )
+-            if ( idx != vcpu_altp2m(v).p2midx )
+-            {
+-                atomic_dec(&p2m_get_altp2m(v)->active_vcpus);
+-                vcpu_altp2m(v).p2midx = idx;
+-                atomic_inc(&p2m_get_altp2m(v)->active_vcpus);
++            if ( p2m_set_altp2m(v, idx) )
+                 altp2m_vcpu_update_p2m(v);
+-            }
+ 
+         rc = 0;
+     }
+diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
+index 2db9ab0122..f92bb97394 100644
+--- a/xen/include/asm-x86/p2m.h
++++ b/xen/include/asm-x86/p2m.h
+@@ -841,6 +841,26 @@ static inline struct p2m_domain *p2m_get_altp2m(struct vcpu *v)
+     return v->domain->arch.altp2m_p2m[index];
+ }
+ 
++/* set current alternate p2m table */
++static inline bool p2m_set_altp2m(struct vcpu *v, unsigned int idx)
++{
++    struct p2m_domain *orig;
++
++    BUG_ON(idx >= MAX_ALTP2M);
++
++    if ( idx == vcpu_altp2m(v).p2midx )
++        return false;
++
++    orig = p2m_get_altp2m(v);
++    BUG_ON(!orig);
++    atomic_dec(&orig->active_vcpus);
++
++    vcpu_altp2m(v).p2midx = idx;
++    atomic_inc(&v->domain->arch.altp2m_p2m[idx]->active_vcpus);
++
++    return true;
++}
++
+ /* Switch alternate p2m for a single vcpu */
+ bool_t p2m_switch_vcpu_altp2m_by_id(struct vcpu *v, unsigned int idx);
+ 
+-- 
+2.40.0
+