[xen staging-4.18] x86/HVM: drop stdvga's "vram_page[]" struct member

[patchbot@xxxxxxx]

commit 4f8e6602bc45008712f9b7828fe0819d259a2472
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Nov 12 13:53:03 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Nov 12 13:53:03 2024 +0100

    x86/HVM: drop stdvga's "vram_page[]" struct member
    
    No uses are left, hence its setup, teardown, and the field itself can
    also go away. stdvga_deinit() is then empty and can be dropped as well.
    
    This is part of XSA-463 / CVE-2024-45818
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    (cherry picked from commit 3beb4baf2a0a2eef40d39eb7e6eecbfd36da5d14)
---
 xen/arch/x86/hvm/hvm.c            |  2 --
 xen/arch/x86/hvm/stdvga.c         | 41 ++++-----------------------------------
 xen/arch/x86/include/asm/hvm/io.h |  2 --
 3 files changed, 4 insertions(+), 41 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 8f293f4feb..3662e23cb6 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -685,7 +685,6 @@ int hvm_domain_initialise(struct domain *d,
     return 0;
 
  fail2:
-    stdvga_deinit(d);
     vioapic_deinit(d);
  fail1:
     if ( is_hardware_domain(d) )
@@ -748,7 +747,6 @@ void hvm_domain_destroy(struct domain *d)
     if ( hvm_funcs.domain_destroy )
         alternative_vcall(hvm_funcs.domain_destroy, d);
 
-    stdvga_deinit(d);
     vioapic_deinit(d);
 
     XFREE(d->arch.hvm.pl_time);
diff --git a/xen/arch/x86/hvm/stdvga.c b/xen/arch/x86/hvm/stdvga.c
index 155a67a438..9f308fc896 100644
--- a/xen/arch/x86/hvm/stdvga.c
+++ b/xen/arch/x86/hvm/stdvga.c
@@ -116,8 +116,7 @@ static const struct hvm_io_ops stdvga_mem_ops = {
 void stdvga_init(struct domain *d)
 {
     struct hvm_hw_stdvga *s = &d->arch.hvm.stdvga;
-    struct page_info *pg;
-    unsigned int i;
+    struct hvm_io_handler *handler;
 
     if ( !has_vvga(d) )
         return;
@@ -125,47 +124,15 @@ void stdvga_init(struct domain *d)
     memset(s, 0, sizeof(*s));
     spin_lock_init(&s->lock);
     
-    for ( i = 0; i != ARRAY_SIZE(s->vram_page); i++ )
+    /* VGA memory */
+    handler = hvm_next_io_handler(d);
+    if ( handler )
     {
-        pg = alloc_domheap_page(d, MEMF_no_owner);
-        if ( pg == NULL )
-            break;
-        s->vram_page[i] = pg;
-        clear_domain_page(page_to_mfn(pg));
-    }
-
-    if ( i == ARRAY_SIZE(s->vram_page) )
-    {
-        struct hvm_io_handler *handler;
-
-        /* VGA memory */
-        handler = hvm_next_io_handler(d);
-
-        if ( handler == NULL )
-            return;
-
         handler->type = IOREQ_TYPE_COPY;
         handler->ops = &stdvga_mem_ops;
     }
 }
 
-void stdvga_deinit(struct domain *d)
-{
-    struct hvm_hw_stdvga *s = &d->arch.hvm.stdvga;
-    int i;
-
-    if ( !has_vvga(d) )
-        return;
-
-    for ( i = 0; i != ARRAY_SIZE(s->vram_page); i++ )
-    {
-        if ( s->vram_page[i] == NULL )
-            continue;
-        free_domheap_page(s->vram_page[i]);
-        s->vram_page[i] = NULL;
-    }
-}
-
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/x86/include/asm/hvm/io.h 
b/xen/arch/x86/include/asm/hvm/io.h
index ec55c93d2f..958077de81 100644
--- a/xen/arch/x86/include/asm/hvm/io.h
+++ b/xen/arch/x86/include/asm/hvm/io.h
@@ -111,12 +111,10 @@ struct vpci_arch_msix_entry {
 };
 
 struct hvm_hw_stdvga {
-    struct page_info *vram_page[64];  /* shadow of 0xa0000-0xaffff */
     spinlock_t lock;
 };
 
 void stdvga_init(struct domain *d);
-void stdvga_deinit(struct domain *d);
 
 extern void hvm_dpci_msi_eoi(struct domain *d, int vector);
 
--
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