[Xen-devel] [PATCH v3 2/2] x86/svm: Add virtual GIF support

[Brian Woods <brian.woods@xxxxxxx>]

This patch detects and enables Virtual GIF if available.  This allows
a nested hypervisor to perform STGIs and CLGIs without having to be
intercepted by host hypervisor.

Signed-off-by: Brian Woods <brian.woods@xxxxxxx>
---
 xen/arch/x86/hvm/svm/nestedsvm.c | 7 ++++++-
 xen/arch/x86/hvm/svm/svm.c       | 1 +
 xen/arch/x86/hvm/svm/vmcb.c      | 9 +++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/svm/nestedsvm.c b/xen/arch/x86/hvm/svm/nestedsvm.c
index 1de896e456..0705cf9cb8 100644
--- a/xen/arch/x86/hvm/svm/nestedsvm.c
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c
@@ -1597,8 +1597,13 @@ bool_t
 nestedsvm_gif_isset(struct vcpu *v)
 {
     struct nestedsvm *svm = &vcpu_nestedsvm(v);
+    struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
 
-    return (!!svm->ns_gif);
+    /* get the vmcb gif value if using vgif */
+    if ( vmcb->_vintr.fields.vgif_enable )
+        return vmcb->_vintr.fields.vgif;
+    else
+        return svm->ns_gif;
 }
 
 void svm_vmexit_do_stgi(struct cpu_user_regs *regs, struct vcpu *v)
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index b9cf423fd9..6b7a462fcb 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1669,6 +1669,7 @@ const struct hvm_function_table * __init start_svm(void)
     P(cpu_has_svm_nrips, "Next-RIP Saved on #VMEXIT");
     P(cpu_has_svm_cleanbits, "VMCB Clean Bits");
     P(cpu_has_svm_decode, "DecodeAssists");
+    P(cpu_has_svm_vgif, "Virtual GIF");
     P(cpu_has_pause_filter, "Pause-Intercept Filter");
     P(cpu_has_tsc_ratio, "TSC Rate MSR");
 #undef P
diff --git a/xen/arch/x86/hvm/svm/vmcb.c b/xen/arch/x86/hvm/svm/vmcb.c
index 997e7597e0..5a714be8f2 100644
--- a/xen/arch/x86/hvm/svm/vmcb.c
+++ b/xen/arch/x86/hvm/svm/vmcb.c
@@ -206,6 +206,15 @@ static int construct_vmcb(struct vcpu *v)
         vmcb->_exception_intercepts |= (1U << TRAP_page_fault);
     }
 
+    /* if available, enable and configure virtual gif */
+    if ( cpu_has_svm_vgif )
+    {
+        vmcb->_vintr.fields.vgif = 1;
+        vmcb->_vintr.fields.vgif_enable = 1;
+        vmcb->_general2_intercepts &= ~GENERAL2_INTERCEPT_STGI;
+        vmcb->_general2_intercepts &= ~GENERAL2_INTERCEPT_CLGI;
+    }
+
     if ( cpu_has_pause_filter )
     {
         vmcb->_pause_filter_count = SVM_PAUSEFILTER_INIT;
-- 
2.11.0


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