[Xen-devel] [PATCH] x86/vvmx: set CR4 before CR0

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

From: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>

Otherwise hvm_set_cr0() will check the wrong CR4 bits (L1 instead of L2
and vice-versa).

Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>

I found this patch languishing in the XenServer patchqueue, and Sergey is OoO
so I'm submitting it on his behalf.

Without this change, nested virt is broken when L1 and L2 differ in their use
of PCID.

This is only a stopgap solution - it resolves the PCID issue without
introducing other issues, but the proper fix needs to consider all control
bits at once, rather than considering a vmentry/exit as a sequence of changes
of discrete registers.
---
 xen/arch/x86/hvm/vmx/vvmx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 7bca572d88..332623d006 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -1024,11 +1024,11 @@ static void load_shadow_guest_state(struct vcpu *v)
     nvcpu->guest_cr[0] = get_vvmcs(v, CR0_READ_SHADOW);
     nvcpu->guest_cr[4] = get_vvmcs(v, CR4_READ_SHADOW);
 
-    rc = hvm_set_cr0(get_vvmcs(v, GUEST_CR0), true);
+    rc = hvm_set_cr4(get_vvmcs(v, GUEST_CR4), true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
-    rc = hvm_set_cr4(get_vvmcs(v, GUEST_CR4), true);
+    rc = hvm_set_cr0(get_vvmcs(v, GUEST_CR0), true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
@@ -1238,11 +1238,11 @@ static void load_vvmcs_host_state(struct vcpu *v)
         __vmwrite(vmcs_h2g_field[i].guest_field, r);
     }
 
-    rc = hvm_set_cr0(get_vvmcs(v, HOST_CR0), true);
+    rc = hvm_set_cr4(get_vvmcs(v, HOST_CR4), true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
-    rc = hvm_set_cr4(get_vvmcs(v, HOST_CR4), true);
+    rc = hvm_set_cr0(get_vvmcs(v, HOST_CR0), true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
-- 
2.11.0


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