From 6aea9e050394e83ac9fbd9fb0cb77c173e5bcae1 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Mon, 13 Apr 2020 16:10:16 -0700 Subject: KVM: arm64: Delete duplicated label in invalid_vector SYM_CODE_START defines \label , so it is redundant to define \label again. A redefinition at the same place is accepted by GNU as (https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=159fbb6088f17a341bcaaac960623cab881b4981) but rejected by the clang integrated assembler. Fixes: 617a2f392c92 ("arm64: kvm: Annotate assembly using modern annoations") Signed-off-by: Fangrui Song Signed-off-by: Marc Zyngier Tested-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Link: https://github.com/ClangBuiltLinux/linux/issues/988 Link: https://lore.kernel.org/r/20200413231016.250737-1-maskray@google.com --- arch/arm64/kvm/hyp/hyp-entry.S | 1 - 1 file changed, 1 deletion(-) (limited to 'arch') diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index c2a13ab3c471..9c5cfb04170e 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -198,7 +198,6 @@ SYM_CODE_END(__hyp_panic) .macro invalid_vector label, target = __hyp_panic .align 2 SYM_CODE_START(\label) -\label: b \target SYM_CODE_END(\label) .endm -- cgit v1.2.3 From 6e977984f6d8e5689e079de1fd2e337cd17dcca5 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 24 Apr 2020 14:24:34 +0100 Subject: KVM: arm64: Save/restore sp_el0 as part of __guest_enter We currently save/restore sp_el0 in C code. This is a bit unsafe, as a lot of the C code expects 'current' to be accessible from there (and the opportunity to run kernel code in HYP is specially great with VHE). Instead, let's move the save/restore of sp_el0 to the assembly code (in __guest_enter), making sure that sp_el0 is correct very early on when we exit the guest, and is preserved as long as possible to its host value when we enter the guest. Reviewed-by: Andrew Jones Acked-by: Mark Rutland Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/entry.S | 23 +++++++++++++++++++++++ arch/arm64/kvm/hyp/sysreg-sr.c | 17 +++-------------- 2 files changed, 26 insertions(+), 14 deletions(-) (limited to 'arch') diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index d22d0534dd60..90186cf6473e 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -18,6 +18,7 @@ #define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x) #define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x) +#define CPU_SP_EL0_OFFSET (CPU_XREG_OFFSET(30) + 8) .text .pushsection .hyp.text, "ax" @@ -47,6 +48,16 @@ ldp x29, lr, [\ctxt, #CPU_XREG_OFFSET(29)] .endm +.macro save_sp_el0 ctxt, tmp + mrs \tmp, sp_el0 + str \tmp, [\ctxt, #CPU_SP_EL0_OFFSET] +.endm + +.macro restore_sp_el0 ctxt, tmp + ldr \tmp, [\ctxt, #CPU_SP_EL0_OFFSET] + msr sp_el0, \tmp +.endm + /* * u64 __guest_enter(struct kvm_vcpu *vcpu, * struct kvm_cpu_context *host_ctxt); @@ -60,6 +71,9 @@ SYM_FUNC_START(__guest_enter) // Store the host regs save_callee_saved_regs x1 + // Save the host's sp_el0 + save_sp_el0 x1, x2 + // Now the host state is stored if we have a pending RAS SError it must // affect the host. If any asynchronous exception is pending we defer // the guest entry. The DSB isn't necessary before v8.2 as any SError @@ -83,6 +97,9 @@ alternative_else_nop_endif // when this feature is enabled for kernel code. ptrauth_switch_to_guest x29, x0, x1, x2 + // Restore the guest's sp_el0 + restore_sp_el0 x29, x0 + // Restore guest regs x0-x17 ldp x0, x1, [x29, #CPU_XREG_OFFSET(0)] ldp x2, x3, [x29, #CPU_XREG_OFFSET(2)] @@ -130,6 +147,9 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) // Store the guest regs x18-x29, lr save_callee_saved_regs x1 + // Store the guest's sp_el0 + save_sp_el0 x1, x2 + get_host_ctxt x2, x3 // Macro ptrauth_switch_to_guest format: @@ -139,6 +159,9 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) // when this feature is enabled for kernel code. ptrauth_switch_to_host x1, x2, x3, x4, x5 + // Restore the hosts's sp_el0 + restore_sp_el0 x2, x3 + // Now restore the host regs restore_callee_saved_regs x2 diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c index 75b1925763f1..6d2df9fe0b5d 100644 --- a/arch/arm64/kvm/hyp/sysreg-sr.c +++ b/arch/arm64/kvm/hyp/sysreg-sr.c @@ -15,8 +15,9 @@ /* * Non-VHE: Both host and guest must save everything. * - * VHE: Host and guest must save mdscr_el1 and sp_el0 (and the PC and pstate, - * which are handled as part of the el2 return state) on every switch. + * VHE: Host and guest must save mdscr_el1 and sp_el0 (and the PC and + * pstate, which are handled as part of the el2 return state) on every + * switch (sp_el0 is being dealt with in the assembly code). * tpidr_el0 and tpidrro_el0 only need to be switched when going * to host userspace or a different VCPU. EL1 registers only need to be * switched when potentially going to run a different VCPU. The latter two @@ -26,12 +27,6 @@ static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt) { ctxt->sys_regs[MDSCR_EL1] = read_sysreg(mdscr_el1); - - /* - * The host arm64 Linux uses sp_el0 to point to 'current' and it must - * therefore be saved/restored on every entry/exit to/from the guest. - */ - ctxt->gp_regs.regs.sp = read_sysreg(sp_el0); } static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt) @@ -99,12 +94,6 @@ NOKPROBE_SYMBOL(sysreg_save_guest_state_vhe); static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt) { write_sysreg(ctxt->sys_regs[MDSCR_EL1], mdscr_el1); - - /* - * The host arm64 Linux uses sp_el0 to point to 'current' and it must - * therefore be saved/restored on every entry/exit to/from the guest. - */ - write_sysreg(ctxt->gp_regs.regs.sp, sp_el0); } static void __hyp_text __sysreg_restore_user_state(struct kvm_cpu_context *ctxt) -- cgit v1.2.3 From 0225fd5e0a6a32af7af0aefac45c8ebf19dc5183 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 29 Apr 2020 11:21:55 +0100 Subject: KVM: arm64: Fix 32bit PC wrap-around In the unlikely event that a 32bit vcpu traps into the hypervisor on an instruction that is located right at the end of the 32bit range, the emulation of that instruction is going to increment PC past the 32bit range. This isn't great, as userspace can then observe this value and get a bit confused. Conversly, userspace can do things like (in the context of a 64bit guest that is capable of 32bit EL0) setting PSTATE to AArch64-EL0, set PC to a 64bit value, change PSTATE to AArch32-USR, and observe that PC hasn't been truncated. More confusion. Fix both by: - truncating PC increments for 32bit guests - sanitizing all 32bit regs every time a core reg is changed by userspace, and that PSTATE indicates a 32bit mode. Cc: stable@vger.kernel.org Acked-by: Will Deacon Signed-off-by: Marc Zyngier --- arch/arm64/kvm/guest.c | 7 +++++++ virt/kvm/arm/hyp/aarch32.c | 8 ++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 23ebe51410f0..50a279d3ddd7 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -200,6 +200,13 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) } memcpy((u32 *)regs + off, valp, KVM_REG_SIZE(reg->id)); + + if (*vcpu_cpsr(vcpu) & PSR_MODE32_BIT) { + int i; + + for (i = 0; i < 16; i++) + *vcpu_reg32(vcpu, i) = (u32)*vcpu_reg32(vcpu, i); + } out: return err; } diff --git a/virt/kvm/arm/hyp/aarch32.c b/virt/kvm/arm/hyp/aarch32.c index d31f267961e7..25c0e47d57cb 100644 --- a/virt/kvm/arm/hyp/aarch32.c +++ b/virt/kvm/arm/hyp/aarch32.c @@ -125,12 +125,16 @@ static void __hyp_text kvm_adjust_itstate(struct kvm_vcpu *vcpu) */ void __hyp_text kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr) { + u32 pc = *vcpu_pc(vcpu); bool is_thumb; is_thumb = !!(*vcpu_cpsr(vcpu) & PSR_AA32_T_BIT); if (is_thumb && !is_wide_instr) - *vcpu_pc(vcpu) += 2; + pc += 2; else - *vcpu_pc(vcpu) += 4; + pc += 4; + + *vcpu_pc(vcpu) = pc; + kvm_adjust_itstate(vcpu); } -- cgit v1.2.3