[09/13] KVM: PPC: Ultravisor: Return to UV for hcalls from SVM

Message ID 1548172784-27414-10-git-send-email-linuxram@us.ibm.com
State New
Headers show
  • KVM: PPC: Paravirtualize KVM to support Ultravisor
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Commit Message

Ram Pai Jan. 22, 2019, 3:59 p.m.
From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>

All hcalls from a secure VM go to the ultravisor from where they are
reflected into the HV. When we (HV) complete processing such hcalls,
we should return to the UV rather than to the guest kernel.

Before reflecting the hcall, the ultravisor sets the MSR_S bit in SRR1
(which gets copied into HSRR1 in kvmppc_interrupt_hv()). If the S bit
is set in HSRR1, return to ultravisor (using UV_RETURN ucall). Otherwise
return to the guest.

Thanks to input from Ram Pai and Mike Anderson.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[fix: UV_RETURN token number]
 arch/powerpc/include/uapi/asm/uapi_uvcall.h |  1 +
 arch/powerpc/kvm/book3s_hv_rmhandlers.S     | 27 ++++++++++++++++++++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)


diff --git a/arch/powerpc/include/uapi/asm/uapi_uvcall.h b/arch/powerpc/include/uapi/asm/uapi_uvcall.h
index bbcd026..b657af6 100644
--- a/arch/powerpc/include/uapi/asm/uapi_uvcall.h
+++ b/arch/powerpc/include/uapi/asm/uapi_uvcall.h
@@ -11,4 +11,5 @@ 
 #define UV_WRITE_PATE 	0xf104
+#define UV_RETURN	0xf11C
 #endif /* #ifndef UAPI_UC_H */
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 9b8d50a..6f2f786 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -35,6 +35,7 @@ 
 #include <asm/thread_info.h>
 #include <asm/asm-compat.h>
 #include <asm/feature-fixups.h>
+#include <asm/ucall-api.h>
 /* Sign-extend HDEC if not on POWER9 */
 #define EXTEND_HDEC(reg)			\
@@ -1092,15 +1093,12 @@  BEGIN_FTR_SECTION
 	ld	r5, VCPU_LR(r4)
-	ld	r6, VCPU_CR(r4)
 	mtlr	r5
-	mtcr	r6
 	ld	r1, VCPU_GPR(R1)(r4)
 	ld	r2, VCPU_GPR(R2)(r4)
 	ld	r3, VCPU_GPR(R3)(r4)
 	ld	r5, VCPU_GPR(R5)(r4)
-	ld	r6, VCPU_GPR(R6)(r4)
 	ld	r7, VCPU_GPR(R7)(r4)
 	ld	r8, VCPU_GPR(R8)(r4)
 	ld	r9, VCPU_GPR(R9)(r4)
@@ -1119,10 +1117,33 @@  BEGIN_FTR_SECTION
 	mtspr	SPRN_HDSISR, r0
+	mfspr	r6, SPRN_HSRR1
+	andis.	r6, r6, MSR_S@high
+	cmplwi	r6, 0
+	bne	ret_to_ultra;
+	lwz	r6, VCPU_CR(r4)
+	mtcr	r6
+	ld	r6, VCPU_GPR(R6)(r4)
 	ld	r0, VCPU_GPR(R0)(r4)
 	ld	r4, VCPU_GPR(R4)(r4)
 	b	.
+ * The hcall we just completed was from Ultravisor. Use UV_RETURN
+ * ultra call to return to the Ultravisor. Results from the hcall
+ * are already in the appropriate registers (r3:12), except for
+ * R6 which we used as a temporary register above. Restore that,
+ * and set R0 to the ucall number (UV_RETURN).
+ */
+	lwz	r6, VCPU_CR(r4)
+	mtcr	r6
+	ld	r6, VCPU_GPR(R6)(r4)
+	ld	r4, VCPU_GPR(R4)(r4)
+	sc	2
  * Enter the guest on a P9 or later system where we have exactly