[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 3/4] xen/hvm: introduce a flags field in the CPU save record
Introduce a new flags field and use bit 0 to signal if the FPU has been initialised or not. Previously Xen always wrongly assumed the FPU was initialised on restore. Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx> Cc: Jan Beulich <jbeulich@xxxxxxxx> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> --- Changes since v3: - Don't add a comment in the compat structure regaring the fpu_initialised field. - Rename fpu_initialised to flags and use it as a bit field. Bit 0 will be used to signal whether the fpu is initialised. - Only save the fpu context if it's initialised. - Only restore the fpu context from the save record if the fpu is initialised. - Check that unused bits in the flags field are 0. Changes since v1: - Don't add yet another compat structure, new fields should always be added to the end of the existing structure and offsetof should be used to compare sizes. - Leave the previous compat structure as-is, since the field was not added to the end we cannot remove it and use offsetof in this case. - Set xstate_bv based on fpu_initialised value instead of unconditionally setting it to XSTATE_FP_SSE. --- xen/arch/x86/hvm/hvm.c | 20 +++++++++++++------- xen/include/public/arch-x86/hvm/save.h | 27 ++++++++++++++++++++------- 2 files changed, 33 insertions(+), 14 deletions(-) diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 141a130..d966074 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -1798,8 +1798,7 @@ static int hvm_save_cpu_ctxt(struct domain *d, hvm_domain_context_t *h) if ( v->fpu_initialised ) memcpy(ctxt.fpu_regs, v->arch.fpu_ctxt, sizeof(ctxt.fpu_regs)); - else - memset(ctxt.fpu_regs, 0, sizeof(ctxt.fpu_regs)); + ctxt.flags = v->fpu_initialised ? XEN_X86_FPU_INITIALISED : 0; ctxt.rax = v->arch.user_regs.eax; ctxt.rbx = v->arch.user_regs.ebx; @@ -1979,7 +1978,7 @@ static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h) return -EINVAL; } - if ( hvm_load_entry(CPU, h, &ctxt) != 0 ) + if ( hvm_load_entry_zeroextend(CPU, h, &ctxt) != 0 ) return -EINVAL; /* Sanity check some control registers. */ @@ -2007,6 +2006,13 @@ static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h) return -EINVAL; } + if ( (ctxt.flags & ~XEN_X86_FPU_INITIALISED) != 0 ) + { + gprintk(XENLOG_ERR, "bad flags value in CPU context: %#x\n", + ctxt.flags); + return -EINVAL; + } + /* Older Xen versions used to save the segment arbytes directly * from the VMCS on Intel hosts. Detect this and rearrange them * into the struct segment_register format. */ @@ -2085,16 +2091,17 @@ static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h) seg.attr.bytes = ctxt.ldtr_arbytes; hvm_set_segment_register(v, x86_seg_ldtr, &seg); + v->fpu_initialised = !!(ctxt.flags & XEN_X86_FPU_INITIALISED); /* In case xsave-absent save file is restored on a xsave-capable host */ - if ( cpu_has_xsave && !xsave_enabled(v) ) + if ( cpu_has_xsave && !xsave_enabled(v) && v->fpu_initialised ) { struct xsave_struct *xsave_area = v->arch.xsave_area; memcpy(v->arch.xsave_area, ctxt.fpu_regs, sizeof(ctxt.fpu_regs)); xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE; } - else - memcpy(v->arch.fpu_ctxt, ctxt.fpu_regs, sizeof(ctxt.fpu_regs)); + else if ( v->fpu_initialised ) + memcpy(v->arch.fpu_ctxt, ctxt.fpu_regs, sizeof(ctxt.fpu_regs)); v->arch.user_regs.eax = ctxt.rax; v->arch.user_regs.ebx = ctxt.rbx; @@ -2122,7 +2129,6 @@ static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h) v->arch.debugreg[7] = ctxt.dr7; v->arch.vgc_flags = VGCF_online; - v->fpu_initialised = 1; /* Auxiliary processors should be woken immediately. */ v->is_initialised = 1; diff --git a/xen/include/public/arch-x86/hvm/save.h b/xen/include/public/arch-x86/hvm/save.h index 29d513c..b6b1bf8 100644 --- a/xen/include/public/arch-x86/hvm/save.h +++ b/xen/include/public/arch-x86/hvm/save.h @@ -47,7 +47,9 @@ DECLARE_HVM_SAVE_TYPE(HEADER, 1, struct hvm_save_header); /* * Processor * - * Compat: Pre-3.4 didn't have msr_tsc_aux + * Compat: + * - Pre-3.4 didn't have msr_tsc_aux + * - Pre-4.7 didn't have fpu_initialised */ struct hvm_hw_cpu { @@ -157,6 +159,10 @@ struct hvm_hw_cpu { }; /* error code for pending event */ uint32_t error_code; + +#define _XEN_X86_FPU_INITIALISED 0 +#define XEN_X86_FPU_INITIALISED (1U<<_XEN_X86_FPU_INITIALISED) + uint32_t flags; }; struct hvm_hw_cpu_compat { @@ -275,12 +281,19 @@ static inline int _hvm_hw_fix_cpu(void *h, uint32_t size) { struct hvm_hw_cpu_compat cmp; } *ucpu = (union hvm_hw_cpu_union *)h; - /* If we copy from the end backwards, we should - * be able to do the modification in-place */ - ucpu->nat.error_code = ucpu->cmp.error_code; - ucpu->nat.pending_event = ucpu->cmp.pending_event; - ucpu->nat.tsc = ucpu->cmp.tsc; - ucpu->nat.msr_tsc_aux = 0; + if ( size == sizeof(struct hvm_hw_cpu_compat) ) + { + /* + * If we copy from the end backwards, we should + * be able to do the modification in-place. + */ + ucpu->nat.error_code = ucpu->cmp.error_code; + ucpu->nat.pending_event = ucpu->cmp.pending_event; + ucpu->nat.tsc = ucpu->cmp.tsc; + ucpu->nat.msr_tsc_aux = 0; + } + /* Mimic the old behaviour by unconditionally setting fpu_initialised. */ + ucpu->nat.flags = XEN_X86_FPU_INITIALISED; return 0; } -- 1.9.5 (Apple Git-50.3) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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