powerpc/kernel: Add ucall_norets() ultravisor call handler (a49dddbd) · Commits · 戴 / test

The ultracalls (ucalls for short) allow the Secure Virtual Machines (SVM)s and hypervisor to request services from the ultravisor such as accessing a register or memory region that can only be accessed when running in ultravisor-privileged mode. This patch adds the ucall_norets() ultravisor call handler. The specific service needed from an ucall is specified in register R3 (the first parameter to the ucall). Other parameters to the ucall, if any, are specified in registers R4 through R12. Return value of all ucalls is in register R3. Other output values from the ucall, if any, are returned in registers R4 through R12. Each ucall returns specific error codes, applicable in the context of the ucall. However, like with the PowerPC Architecture Platform Reference (PAPR), if no specific error code is defined for a particular situation, then the ucall will fallback to an erroneous parameter-position based code. i.e U_PARAMETER, U_P2, U_P3 etc depending on the ucall parameter that may have caused the error. Every host kernel (powernv) needs to be able to do ucalls in case it ends up being run in a machine with ultravisor enabled. Otherwise, the kernel may crash early in boot trying to access ultravisor resources, for instance, trying to set the partition table entry 0. Secure guests also need to be able to do ucalls and its kernel may not have CONFIG_PPC_POWERNV=y. For that reason, the ucall.S file is placed under arch/powerpc/kernel. If ultravisor is not enabled, the ucalls will be redirected to the hypervisor which must handle/fail the call. Thanks to inputs from Ram Pai and Michael Anderson. Signed-off-by:

Claudio Carvalho <cclaudio@linux.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190822034838.27876-3-cclaudio@linux.ibm.com

arch/powerpc/include/asm/asm-prototypes.h

+11 −0

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@
		#include <asm/epapr_hcalls.h>
		#include <asm/dcr.h>
		#include <asm/mmu_context.h>
		#include <asm/ultravisor-api.h>

		#include <uapi/asm/ucontext.h>

		@@ -34,6 +35,16 @@ extern struct static_key hcall_tracepoint_key;
		void __trace_hcall_entry(unsigned long opcode, unsigned long *args);
		void __trace_hcall_exit(long opcode, long retval, unsigned long *retbuf);

		/* Ultravisor */
		#ifdef CONFIG_PPC_POWERNV
		long ucall_norets(unsigned long opcode, ...);
		#else
		static inline long ucall_norets(unsigned long opcode, ...)
		{
		return U_NOT_AVAILABLE;
		}
		#endif

		/* OPAL */
		int64_t __opal_call(int64_t a0, int64_t a1, int64_t a2, int64_t a3,
		int64_t a4, int64_t a5, int64_t a6, int64_t a7,

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

0 → 100644

+23 −0

Original line number	Diff line number	Diff line
		/* SPDX-License-Identifier: GPL-2.0 */
		/*
		* Ultravisor API.
		*
		* Copyright 2019, IBM Corporation.
		*
		*/
		#ifndef _ASM_POWERPC_ULTRAVISOR_API_H
		#define _ASM_POWERPC_ULTRAVISOR_API_H

		#include <asm/hvcall.h>

		/* Return codes */
		#define U_FUNCTION H_FUNCTION
		#define U_NOT_AVAILABLE H_NOT_AVAILABLE
		#define U_P2 H_P2
		#define U_P3 H_P3
		#define U_P4 H_P4
		#define U_P5 H_P5
		#define U_PARAMETER H_PARAMETER
		#define U_SUCCESS H_SUCCESS

		#endif /* _ASM_POWERPC_ULTRAVISOR_API_H */

arch/powerpc/kernel/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -156,6 +156,7 @@ endif

		obj-$(CONFIG_EPAPR_PARAVIRT) += epapr_paravirt.o epapr_hcalls.o
		obj-$(CONFIG_KVM_GUEST) += kvm.o kvm_emul.o
		obj-$(CONFIG_PPC_POWERNV) += ucall.o

		# Disable GCOV, KCOV & sanitizers in odd or sensitive code
		GCOV_PROFILE_prom_init.o := n

arch/powerpc/kernel/ucall.S

0 → 100644

+14 −0

Original line number	Diff line number	Diff line
		/* SPDX-License-Identifier: GPL-2.0 */
		/*
		* Generic code to perform an ultravisor call.
		*
		* Copyright 2019, IBM Corporation.
		*
		*/
		#include <asm/ppc_asm.h>
		#include <asm/export.h>

		_GLOBAL(ucall_norets)
		EXPORT_SYMBOL_GPL(ucall_norets)
		sc 2 /* Invoke the ultravisor */
		blr /* Return r3 = status */

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