From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>,
Nadav Amit <namit@cs.technion.ac.il>,
kvm@vger.kernel.org
Subject: Re: [PATCH 08/21] KVM: x86: Reset FPU state during reset
Date: Thu, 6 Nov 2014 18:38:09 +0100 [thread overview]
Message-ID: <20141106173808.GA3584@potion.brq.redhat.com> (raw)
In-Reply-To: <545B42FF.4000302@redhat.com>
2014-11-06 10:44+0100, Paolo Bonzini:
>
>
> On 06/11/2014 10:13, Nadav Amit wrote:
> >
> >> On Nov 6, 2014, at 10:58, Paolo Bonzini <pbonzini@redhat.com> wrote:
> >>
> >> On 05/11/2014 21:31, Nadav Amit wrote:
> >>> You are correct, it does not appear clearly in the SDM, but that is what real hardware does.
> >>> If you look at bochs - http://code.metager.de/source/xref/bochs/bochs/cpu/init.cc - you’ll see they call
> >>> "BX_CPU_THIS_PTR xcr0.set32(0x1);” regardless to whether it is hardware or software reset (the latter happens on INIT).
> >>
> >> Fair enough. :)
> > Thanks. It is turning harder to find references for the crazy x86 behaviour. :)
>
> Indeed, I'll ask Intel to clarify this one too.
>
> The crazy thing is that AMD doesn't say anything, either! Their own
> manual just says "Hardware initializes XCR0 to 0000_0000_0000_0001h",
> but it doesn't say when.
I found AMD 2:15.21.8
INIT reinitializes the control registers, segment registers and GP
registers in a manner similar to RESET, but does not alter the
contents of most MSRs, caches or numeric coprocessor (x87 or SSE)
state,
So reseting XCR0 is ok, but we shouldn't call fx_init() on INIT,
the version below seems fine in this regard.
next prev parent reply other threads:[~2014-11-06 17:38 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-02 9:54 [PATCH 00/21] Fixes for various KVM bugs Nadav Amit
2014-11-02 9:54 ` [PATCH 01/21] KVM: x86: decode_modrm does not regard modrm correctly Nadav Amit
2014-11-05 11:14 ` Paolo Bonzini
2014-11-02 9:54 ` [PATCH 02/21] KVM: x86: No error-code on real-mode exceptions Nadav Amit
2014-11-02 9:54 ` [PATCH 03/21] KVM: x86: Emulator should set DR6 upon GD like real CPU Nadav Amit
2014-11-02 9:54 ` [PATCH 04/21] KVM: x86: Clear DR6[0:3] on #DB during handle_dr Nadav Amit
2014-11-02 9:54 ` [PATCH 05/21] KVM: x86: Breakpoints do not consider CS.base Nadav Amit
2014-11-02 9:54 ` [PATCH 06/21] KVM: x86: Emulator MOV-sreg uses incorrect size Nadav Amit
2014-11-05 11:28 ` Paolo Bonzini
2014-11-02 9:54 ` [PATCH 07/21] KVM: x86: Emulator considers imm as memory operand Nadav Amit
2014-11-05 11:36 ` Paolo Bonzini
2014-11-02 9:54 ` [PATCH 08/21] KVM: x86: Reset FPU state during reset Nadav Amit
2014-11-05 12:04 ` Paolo Bonzini
2014-11-05 13:20 ` Nadav Amit
2014-11-05 14:55 ` Paolo Bonzini
2014-11-05 20:31 ` Nadav Amit
2014-11-06 8:58 ` Paolo Bonzini
2014-11-06 9:13 ` Nadav Amit
2014-11-06 9:44 ` Paolo Bonzini
2014-11-06 9:56 ` Nadav Amit
2014-11-06 10:44 ` Paolo Bonzini
2014-11-06 17:38 ` Radim Krčmář [this message]
2014-11-02 9:54 ` [PATCH 09/21] KVM: x86: SYSCALL cannot clear eflags[1] Nadav Amit
2014-11-02 9:54 ` [PATCH 10/21] KVM: x86: Wrong flags on CMPS and SCAS emulation Nadav Amit
2014-11-02 9:54 ` [PATCH 11/21] KVM: x86: Emulate push sreg as done in Core Nadav Amit
2014-11-02 9:54 ` [PATCH 12/21] KVM: x86: MOV to CR3 can set bit 63 Nadav Amit
2015-02-10 16:15 ` Jan Kiszka
2015-02-10 16:18 ` Paolo Bonzini
2015-02-10 16:34 ` Jan Kiszka
2015-02-10 16:42 ` Paolo Bonzini
2014-11-02 9:54 ` [PATCH 13/21] KVM: x86: Do not update EFLAGS on faulting emulation Nadav Amit
2014-11-02 9:54 ` [PATCH 14/21] KVM: x86: Software disabled APIC should still deliver NMIs Nadav Amit
2014-11-05 12:30 ` Paolo Bonzini
2014-11-05 20:45 ` Nadav Amit
2014-11-06 9:34 ` Paolo Bonzini
2014-11-06 16:45 ` Radim Krčmář
2014-11-10 17:35 ` Paolo Bonzini
2014-11-10 18:06 ` Radim Krčmář
2014-11-14 15:00 ` Paolo Bonzini
2014-11-26 17:01 ` Nadav Amit
2014-11-26 18:00 ` Paolo Bonzini
2014-11-27 13:39 ` Radim Krčmář
2014-11-27 21:45 ` Nadav Amit
2014-11-27 22:26 ` Radim Krčmář
2014-12-01 16:30 ` Paolo Bonzini
2014-12-01 17:49 ` Radim Krčmář
2014-11-02 9:54 ` [PATCH 15/21] KVM: x86: Combine the lgdt and lidt emulation logic Nadav Amit
2014-11-02 9:54 ` [PATCH 16/21] KVM: x86: Inject #GP when loading system segments with non-canonical base Nadav Amit
2014-11-02 9:54 ` [PATCH 17/21] KVM: x86: Remove redundant and incorrect cpl check on task-switch Nadav Amit
2014-11-02 9:54 ` [PATCH 18/21] KVM: x86: Emulator mis-decodes VEX instructions on real-mode Nadav Amit
2014-11-08 7:25 ` Paolo Bonzini
2014-11-02 9:54 ` [PATCH 19/21] KVM: x86: Warn on APIC base relocation Nadav Amit
2014-11-02 9:55 ` [PATCH 20/21] KVM: x86: MOVNTI emulation min opsize is not respected Nadav Amit
2014-11-05 12:18 ` Paolo Bonzini
2014-11-05 19:58 ` Nadav Amit
2014-11-05 19:58 ` Nadav Amit
2014-11-06 9:23 ` Paolo Bonzini
2014-11-02 9:55 ` [PATCH 21/21] KVM: x86: Return UNHANDLABLE on unsupported SYSENTER Nadav Amit
2014-11-05 12:31 ` [PATCH 00/21] Fixes for various KVM bugs Paolo Bonzini
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