Commit 6c85b7bc authored by Sukadev Bhattiprolu's avatar Sukadev Bhattiprolu Committed by Michael Ellerman
Browse files

powerpc/kvm: Use UV_RETURN ucall to return to ultravisor 



When an SVM makes an hypercall or incurs some other exception, the
Ultravisor usually forwards (a.k.a. reflects) the exceptions to the
Hypervisor. After processing the exception, Hypervisor uses the
UV_RETURN ultracall to return control back to the SVM.

The expected register state on entry to this ultracall is:

* Non-volatile registers are restored to their original values.
* If returning from an hypercall, register R0 contains the return value
  (unlike other ultracalls) and, registers R4 through R12 contain any
  output values of the hypercall.
* R3 contains the ultracall number, i.e UV_RETURN.
* If returning with a synthesized interrupt, R2 contains the
  synthesized interrupt number.

Thanks to input from Paul Mackerras, Ram Pai and Mike Anderson.

Signed-off-by: default avatarSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: default avatarClaudio Carvalho <cclaudio@linux.ibm.com>
Acked-by: default avatarPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190822034838.27876-8-cclaudio@linux.ibm.com
parent 512a5a64

arch/powerpc/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -283,6 +283,7 @@ struct kvm_arch { 
	cpumask_t cpu_in_guest;

	u8 radix;

	u8 fwnmi_enabled;

	u8 secure_guest;

	bool threads_indep;

	bool nested_enable;

	pgd_t *pgtable;

arch/powerpc/include/asm/ultravisor-api.h

+1 −0
Original line number Diff line number Diff line
@@ -24,5 +24,6 @@ 


/* opcodes */

#define UV_WRITE_PATE			0xF104

#define UV_RETURN			0xF11C



#endif /* _ASM_POWERPC_ULTRAVISOR_API_H */

arch/powerpc/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -506,6 +506,7 @@ int main(void) 
	OFFSET(KVM_VRMA_SLB_V, kvm, arch.vrma_slb_v);

	OFFSET(KVM_RADIX, kvm, arch.radix);

	OFFSET(KVM_FWNMI, kvm, arch.fwnmi_enabled);

	OFFSET(KVM_SECURE_GUEST, kvm, arch.secure_guest);

	OFFSET(VCPU_DSISR, kvm_vcpu, arch.shregs.dsisr);

	OFFSET(VCPU_DAR, kvm_vcpu, arch.shregs.dar);

	OFFSET(VCPU_VPA, kvm_vcpu, arch.vpa.pinned_addr);

arch/powerpc/kvm/book3s_hv_rmhandlers.S

+33 −6
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <asm/asm-compat.h>

#include <asm/feature-fixups.h>

#include <asm/cpuidle.h>

#include <asm/ultravisor-api.h>



/* Sign-extend HDEC if not on POWER9 */

#define EXTEND_HDEC(reg)			\
@@ -1085,16 +1086,10 @@ BEGIN_FTR_SECTION 
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)



	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)

	ld	r10, VCPU_GPR(R10)(r4)
@@ -1112,10 +1107,42 @@ BEGIN_FTR_SECTION 
	mtspr	SPRN_HDSISR, r0

END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)



	ld	r6, VCPU_KVM(r4)

	lbz	r7, KVM_SECURE_GUEST(r6)

	cmpdi	r7, 0

	ld	r6, VCPU_GPR(R6)(r4)

	ld	r7, VCPU_GPR(R7)(r4)

	bne	ret_to_ultra



	lwz	r0, VCPU_CR(r4)

	mtcr	r0



	ld	r0, VCPU_GPR(R0)(r4)

	ld	r2, VCPU_GPR(R2)(r4)

	ld	r3, VCPU_GPR(R3)(r4)

	ld	r4, VCPU_GPR(R4)(r4)

	HRFI_TO_GUEST

	b	.

/*

 * Use UV_RETURN ultracall to return control back to the Ultravisor after

 * processing an hypercall or interrupt that was forwarded (a.k.a. reflected)

 * to the Hypervisor.

 *

 * All registers have already been loaded, except:

 *   R0 = hcall result

 *   R2 = SRR1, so UV can detect a synthesized interrupt (if any)

 *   R3 = UV_RETURN

 */

ret_to_ultra:

	lwz	r0, VCPU_CR(r4)

	mtcr	r0



	ld	r0, VCPU_GPR(R3)(r4)

	mfspr	r2, SPRN_SRR1

	li	r3, 0

	ori	r3, r3, UV_RETURN

	ld	r4, VCPU_GPR(R4)(r4)

	sc	2



/*

 * Enter the guest on a P9 or later system where we have exactly

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