From 839826b094a068139fa38e56e52e9f054cca8823 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 28 Jun 2018 11:29:48 +0200 Subject: [PATCH] x86/EFI: further correct FPU state handling around runtime calls We must not leave a vCPU with CR0.TS clear when it is not in fully eager mode and has not touched non-lazy state. Instead of adding a 3rd invocation of stts() to vcpu_restore_fpu_eager(), consolidate all of them into a single one done at the end of the function. Rename the function at the same time to better reflect its purpose, as the patches touches all of its occurences anyway. The new function parameter is not really well named, but "need_stts_if_not_fully_eager" seemed excessive to me. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper Reviewed-by: Paul Durrant master commit: 23839a0fa0bbe78c174cd2bb49083e153f0f99df master date: 2018-06-26 15:23:08 +0200 --- xen/arch/x86/domain.c | 2 +- xen/arch/x86/i387.c | 13 ++++++++----- xen/common/efi/runtime.c | 2 +- xen/include/asm-x86/i387.h | 2 +- 4 files changed, 11 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index a3e913b162..596be5c4f5 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -2147,7 +2147,7 @@ static void __context_switch(void) if ( cpu_has_xsaves && has_hvm_container_vcpu(n) ) set_msr_xss(n->arch.hvm_vcpu.msr_xss); } - vcpu_restore_fpu_eager(n); + vcpu_restore_fpu_nonlazy(n, 0); n->arch.ctxt_switch_to(n); } diff --git a/xen/arch/x86/i387.c b/xen/arch/x86/i387.c index 992d4d21c1..286847148a 100644 --- a/xen/arch/x86/i387.c +++ b/xen/arch/x86/i387.c @@ -207,11 +207,11 @@ static inline void fpu_fxsave(struct vcpu *v) /* VCPU FPU Functions */ /*******************************/ /* Restore FPU state whenever VCPU is schduled in. */ -void vcpu_restore_fpu_eager(struct vcpu *v) +void vcpu_restore_fpu_nonlazy(struct vcpu *v, bool_t need_stts) { /* Restore nonlazy extended state (i.e. parts not tracked by CR0.TS). */ if ( !v->arch.fully_eager_fpu && !v->arch.nonlazy_xstate_used ) - return; + goto maybe_stts; ASSERT(!is_idle_vcpu(v)); @@ -234,14 +234,17 @@ void vcpu_restore_fpu_eager(struct vcpu *v) v->fpu_dirtied = 1; /* Xen doesn't need TS set, but the guest might. */ - if ( is_pv_vcpu(v) && (v->arch.pv_vcpu.ctrlreg[0] & X86_CR0_TS) ) - stts(); + need_stts = is_pv_vcpu(v) && (v->arch.pv_vcpu.ctrlreg[0] & X86_CR0_TS); } else { fpu_xrstor(v, XSTATE_NONLAZY); - stts(); + need_stts = 1; } + + maybe_stts: + if ( need_stts ) + stts(); } /* diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c index 65402e2d1f..f53101a5e5 100644 --- a/xen/common/efi/runtime.c +++ b/xen/common/efi/runtime.c @@ -130,7 +130,7 @@ void efi_rs_leave(struct efi_rs_state *state) irq_exit(); efi_rs_on_cpu = NR_CPUS; spin_unlock(&efi_rs_lock); - vcpu_restore_fpu_eager(curr); + vcpu_restore_fpu_nonlazy(curr, 1); } bool_t efi_rs_using_pgtables(void) diff --git a/xen/include/asm-x86/i387.h b/xen/include/asm-x86/i387.h index 7cfa215d30..5a4d778033 100644 --- a/xen/include/asm-x86/i387.h +++ b/xen/include/asm-x86/i387.h @@ -28,7 +28,7 @@ struct ix87_env { uint16_t fds, _res6; }; -void vcpu_restore_fpu_eager(struct vcpu *v); +void vcpu_restore_fpu_nonlazy(struct vcpu *v, bool_t need_stts); void vcpu_restore_fpu_lazy(struct vcpu *v); void vcpu_save_fpu(struct vcpu *v); void save_fpu_enable(void); -- 2.39.5