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Commit 0d17aea5 authored by James Hogan's avatar James Hogan Committed by Paolo Bonzini
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MIPS: KVM: Use 64-bit CP0_EBase when appropriate 



Update the KVM entry point to write CP0_EBase as a 64-bit register when
it is 64-bits wide, and to set the WG (write gate) bit if it exists in
order to write bits 63:30 (or 31:30 on MIPS32).

Prior to MIPS64r6 it was UNDEFINED to perform a 64-bit read or write of
a 32-bit COP0 register. Since this is dynamically generated code,
generate the right type of access depending on whether the kernel is
64-bit and cpu_has_ebase_wg.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 1d756942

arch/mips/kvm/entry.c

+22 −3
Original line number Diff line number Diff line
@@ -152,6 +152,25 @@ static void kvm_mips_build_restore_scratch(u32 **p, unsigned int tmp, 
	}

}



/**

 * build_set_exc_base() - Assemble code to write exception base address.

 * @p:		Code buffer pointer.

 * @reg:	Source register (generated code may set WG bit in @reg).

 *

 * Assemble code to modify the exception base address in the EBase register,

 * using the appropriately sized access and setting the WG bit if necessary.

 */

static inline void build_set_exc_base(u32 **p, unsigned int reg)

{

	if (cpu_has_ebase_wg) {

		/* Set WG so that all the bits get written */

		uasm_i_ori(p, reg, reg, MIPS_EBASE_WG);

		UASM_i_MTC0(p, reg, C0_EBASE);

	} else {

		uasm_i_mtc0(p, reg, C0_EBASE);

	}

}



/**

 * kvm_mips_build_vcpu_run() - Assemble function to start running a guest VCPU.

 * @addr:	Address to start writing code.
@@ -216,7 +235,7 @@ void *kvm_mips_build_vcpu_run(void *addr) 


	/* load up the new EBASE */

	UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, guest_ebase), K1);

	uasm_i_mtc0(&p, K0, C0_EBASE);

	build_set_exc_base(&p, K0);



	/*

	 * Now that the new EBASE has been loaded, unset BEV, set
@@ -463,7 +482,7 @@ void *kvm_mips_build_exit(void *addr) 


	UASM_i_LA_mostly(&p, K0, (long)&ebase);

	UASM_i_LW(&p, K0, uasm_rel_lo((long)&ebase), K0);

	uasm_i_mtc0(&p, K0, C0_EBASE);

	build_set_exc_base(&p, K0);



	if (raw_cpu_has_fpu) {

		/*
@@ -620,7 +639,7 @@ static void *kvm_mips_build_ret_to_guest(void *addr) 
	uasm_i_or(&p, K0, V1, AT);

	uasm_i_mtc0(&p, K0, C0_STATUS);

	uasm_i_ehb(&p);

	uasm_i_mtc0(&p, T0, C0_EBASE);

	build_set_exc_base(&p, T0);



	/* Setup status register for running guest in UM */

	uasm_i_ori(&p, V1, V1, ST0_EXL | KSU_USER | ST0_IE);