x86/domctl: remove PV MSR parts of XEN_DOMCTL_[gs]et_ext_vcpucontext

The PV MSR functionality is now implemented as a separate set of domctls.

This is a revert of parts of c/s65e3554908
  "x86/PV: support data breakpoint extension registers"

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/domctl.c

@@ -818,7 +818,6 @@ long arch_do_domctl(
     {
         struct xen_domctl_ext_vcpucontext *evc;
         struct vcpu *v;
-        struct xen_domctl_ext_vcpu_msr msr;
 
         evc = &domctl->u.ext_vcpucontext;
 
@@ -864,42 +863,7 @@ long arch_do_domctl(
             evc->vmce.mci_ctl2_bank0 = v->arch.vmce.bank[0].mci_ctl2;
             evc->vmce.mci_ctl2_bank1 = v->arch.vmce.bank[1].mci_ctl2;
 
-            i = ret = 0;
-            if ( boot_cpu_has(X86_FEATURE_DBEXT) )
-            {
-                unsigned int j;
-
-                if ( v->arch.pv_vcpu.dr_mask[0] )
-                {
-                    if ( i < evc->msr_count && !ret )
-                    {
-                        msr.index = MSR_AMD64_DR0_ADDRESS_MASK;
-                        msr.reserved = 0;
-                        msr.value = v->arch.pv_vcpu.dr_mask[0];
-                        if ( copy_to_guest_offset(evc->msrs, i, &msr, 1) )
-                            ret = -EFAULT;
-                    }
-                    ++i;
-                }
-                for ( j = 0; j < 3; ++j )
-                {
-                    if ( !v->arch.pv_vcpu.dr_mask[1 + j] )
-                        continue;
-                    if ( i < evc->msr_count && !ret )
-                    {
-                        msr.index = MSR_AMD64_DR1_ADDRESS_MASK + j;
-                        msr.reserved = 0;
-                        msr.value = v->arch.pv_vcpu.dr_mask[1 + j];
-                        if ( copy_to_guest_offset(evc->msrs, i, &msr, 1) )
-                            ret = -EFAULT;
-                    }
-                    ++i;
-                }
-            }
-            if ( i > evc->msr_count && !ret )
-                ret = -ENOBUFS;
-            evc->msr_count = i;
-
+            ret = 0;
             vcpu_unpause(v);
             copyback = 1;
         }
@@ -954,49 +918,9 @@ long arch_do_domctl(
 
                 ret = vmce_restore_vcpu(v, &vmce);
             }
-            else if ( evc->size > offsetof(typeof(*evc), vmce) )
-                ret = -EINVAL;
             else
                 ret = 0;
 
-            if ( ret || evc->size <= offsetof(typeof(*evc), msrs) )
-                /* nothing */;
-            else if ( evc->size < offsetof(typeof(*evc), msrs) +
-                                  sizeof(evc->msrs) )
-                ret = -EINVAL;
-            else
-            {
-                for ( i = 0; i < evc->msr_count; ++i )
-                {
-                    ret = -EFAULT;
-                    if ( copy_from_guest_offset(&msr, evc->msrs, i, 1) )
-                        break;
-                    ret = -EINVAL;
-                    if ( msr.reserved )
-                        break;
-                    switch ( msr.index )
-                    {
-                    case MSR_AMD64_DR0_ADDRESS_MASK:
-                        if ( !boot_cpu_has(X86_FEATURE_DBEXT) ||
-                             (msr.value >> 32) )
-                            break;
-                        v->arch.pv_vcpu.dr_mask[0] = msr.value;
-                        continue;
-                    case MSR_AMD64_DR1_ADDRESS_MASK ...
-                         MSR_AMD64_DR3_ADDRESS_MASK:
-                        if ( !boot_cpu_has(X86_FEATURE_DBEXT) ||
-                             (msr.value >> 32) )
-                            break;
-                        msr.index -= MSR_AMD64_DR1_ADDRESS_MASK - 1;
-                        v->arch.pv_vcpu.dr_mask[msr.index] = msr.value;
-                        continue;
-                    }
-                    break;
-                }
-                if ( i == evc->msr_count )
-                    ret = 0;
-            }
-
             domain_unpause(d);
         }
     }

xen/include/public/domctl.h

@@ -543,16 +543,6 @@ typedef struct xen_domctl_pin_mem_cacheattr xen_domctl_pin_mem_cacheattr_t;
 DEFINE_XEN_GUEST_HANDLE(xen_domctl_pin_mem_cacheattr_t);
 
 
-#if defined(__i386__) || defined(__x86_64__)
-struct xen_domctl_ext_vcpu_msr {
-    uint32_t         index;
-    uint32_t         reserved;
-    uint64_aligned_t value;
-};
-typedef struct xen_domctl_ext_vcpu_msr xen_domctl_ext_vcpu_msr_t;
-DEFINE_XEN_GUEST_HANDLE(xen_domctl_ext_vcpu_msr_t);
-#endif
-
 /* XEN_DOMCTL_set_ext_vcpucontext */
 /* XEN_DOMCTL_get_ext_vcpucontext */
 struct xen_domctl_ext_vcpucontext {
@@ -572,14 +562,6 @@ struct xen_domctl_ext_vcpucontext {
     uint16_t         sysenter_callback_cs;
     uint8_t          syscall32_disables_events;
     uint8_t          sysenter_disables_events;
-    /*
-     * When, for the "get" version, msr_count is too small to cover all MSRs
-     * the hypervisor needs to be saved, the call will return -ENOBUFS and
-     * set msr_count to the required (minimum) value. Furthermore, for both
-     * "get" and "set", that field as well as the msrs one only get looked at
-     * if the size field above covers the structure up to the entire msrs one.
-     */
-    uint16_t         msr_count;
 #if defined(__GNUC__)
     union {
         uint64_aligned_t mcg_cap;
@@ -588,7 +570,6 @@ struct xen_domctl_ext_vcpucontext {
 #else
     struct hvm_vmce_vcpu vmce;
 #endif
-    XEN_GUEST_HANDLE_64(xen_domctl_ext_vcpu_msr_t) msrs;
 #endif
 };
 typedef struct xen_domctl_ext_vcpucontext xen_domctl_ext_vcpucontext_t;