From 0d17aea5c27d7d748b1d8116d275b2b17dc5cad6 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Fri, 8 Jul 2016 11:53:25 +0100 Subject: [PATCH] MIPS: KVM: Use 64-bit CP0_EBase when appropriate MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: James Hogan Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/mips/kvm/entry.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) diff --git a/arch/mips/kvm/entry.c b/arch/mips/kvm/entry.c index c824bfc4daa0..6a02b3a3fa65 100644 --- a/arch/mips/kvm/entry.c +++ b/arch/mips/kvm/entry.c @@ -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); -- 2.20.1