struct nestedvm uses mostly plain integer types, except for virt_ext_t which
is a union wrapping two bitfield names.

However, it turns out that this is a write-only variable.  Delete it, allowing
us to drop the include of vmcb.h

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Xenia Ragiadakou <burzalodowa@gmail.com>

v2:
 * Delete the variable entirely.

This probably means that nested lbr/vmloadsave is broken, but that wouldn't be
a surprise at all.
---
 xen/arch/x86/hvm/svm/nestedsvm.c             | 5 -----
 xen/arch/x86/include/asm/hvm/svm/nestedsvm.h | 5 -----
 2 files changed, 10 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/nestedsvm.c b/xen/arch/x86/hvm/svm/nestedsvm.c
index 92316c6624ce..63ed9fc248e1 100644
--- a/xen/arch/x86/hvm/svm/nestedsvm.c
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c
@@ -164,7 +164,6 @@ int cf_check nsvm_vcpu_reset(struct vcpu *v)
     svm->ns_exception_intercepts = 0;
     svm->ns_general1_intercepts = 0;
     svm->ns_general2_intercepts = 0;
-    svm->ns_virt_ext.bytes = 0;
 
     svm->ns_hap_enabled = 0;
     svm->ns_vmcb_guestcr3 = 0;
@@ -524,10 +523,6 @@ static int nsvm_vmcb_prepare4vmrun(struct vcpu *v, struct cpu_user_regs *regs)
     /* Pending Interrupts */
     n2vmcb->event_inj = ns_vmcb->event_inj;
 
-    /* LBR and other virtualization */
-    if ( !clean.lbr )
-        svm->ns_virt_ext = ns_vmcb->virt_ext;
-
     n2vmcb->virt_ext.bytes =
         n1vmcb->virt_ext.bytes | ns_vmcb->virt_ext.bytes;
 
diff --git a/xen/arch/x86/include/asm/hvm/svm/nestedsvm.h b/xen/arch/x86/include/asm/hvm/svm/nestedsvm.h
index 94d45d2e8d47..230f818df80c 100644
--- a/xen/arch/x86/include/asm/hvm/svm/nestedsvm.h
+++ b/xen/arch/x86/include/asm/hvm/svm/nestedsvm.h
@@ -20,8 +20,6 @@
 
 #include <xen/types.h>
 
-#include <asm/hvm/svm/vmcb.h>
-
 struct nestedsvm {
     bool ns_gif;
     uint64_t ns_msr_hsavepa; /* MSR HSAVE_PA value */
@@ -43,9 +41,6 @@ struct nestedsvm {
     uint32_t ns_general1_intercepts;
     uint32_t ns_general2_intercepts;
 
-    /* Cached real lbr and other virtual extentions of the l2 guest */
-    virt_ext_t ns_virt_ext;
-
     /* Cached real MSR permission bitmaps of the l2 guest */
     unsigned long *ns_cached_msrpm;
     /* Merged MSR permission bitmap */
-- 
2.30.2

On 27.02.2023 12:35, Andrew Cooper wrote:
> struct nestedvm uses mostly plain integer types, except for virt_ext_t which
> is a union wrapping two bitfield names.
> 
> However, it turns out that this is a write-only variable.  Delete it, allowing
> us to drop the include of vmcb.h
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Xenia Ragiadakou <burzalodowa@gmail.com>
> 
> v2:
>  * Delete the variable entirely.
> 
> This probably means that nested lbr/vmloadsave is broken, but that wouldn't be
> a surprise at all.

Well, yes, short of figuring out what's missing this is probably the least
bad option:
Reviewed-by: Jan Beulich <jbeulich@suse.com>

Jan

On 27/02/2023 11:41 am, Jan Beulich wrote:
> On 27.02.2023 12:35, Andrew Cooper wrote:
>> struct nestedvm uses mostly plain integer types, except for virt_ext_t which
>> is a union wrapping two bitfield names.
>>
>> However, it turns out that this is a write-only variable.  Delete it, allowing
>> us to drop the include of vmcb.h
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
>> ---
>> CC: Jan Beulich <JBeulich@suse.com>
>> CC: Xenia Ragiadakou <burzalodowa@gmail.com>
>>
>> v2:
>>  * Delete the variable entirely.
>>
>> This probably means that nested lbr/vmloadsave is broken, but that wouldn't be
>> a surprise at all.
> Well, yes, short of figuring out what's missing this is probably the least
> bad option:
> Reviewed-by: Jan Beulich <jbeulich@suse.com>

Thanks.

I'm pretty certain a working version of nested virt won't need this
cached information like this at all.  I'm pretty sure it's buggy not to
be referencing the appropriate one of the 3 relevant VMCBs.

~Andrew