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From: Joerg Roedel <joro@8bytes.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, Joerg Roedel <jroedel@suse.de>,
	hpa@zytor.com, Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Jiri Slaby <jslaby@suse.cz>,
	Dan Williams <dan.j.williams@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Juergen Gross <jgross@suse.com>,
	Kees Cook <keescook@chromium.org>,
	David Rientjes <rientjes@google.com>,
	Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <seanjc@google.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v3 4/7] x86/sev-es: Run #VC handler in plain IRQ state
Date: Tue, 8 Jun 2021 15:25:51 +0200	[thread overview]
Message-ID: <YL9v38J0JC5FrZnM@8bytes.org> (raw)
In-Reply-To: <YL9bd2hx/y9oD6x/@hirez.programming.kicks-ass.net>

Hi Peter,

On Tue, Jun 08, 2021 at 01:58:47PM +0200, Peter Zijlstra wrote:
> So #VC cannot happen with IRQs disabled?
> 
> 	raw_spin_lock_irq(&my_lock);
> 	<#VC>
> 		raw_spin_lock_irqsave(&my_lock); // whoopsie
> 
> Every exception that can happen with IRQs disabled must be NMI like.
> 
> Again, what you seem to want is to split the handler in a from-user and
> from-kernel way, just like we did with #DB and MCE. See how
> exc_debug_user() is IRQ-like and can send signals, while
> exc_debug_kernel() is NMI like and can not.

You are right, thanks for pointing this out. I replaced that patch by
one implementing the split in a from-user and from-kernel part. Initial
testing looks good, will send it out later this week.

Thanks,

	Joerg


WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: kvm@vger.kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
	virtualization@lists.linux-foundation.org,
	Arvind Sankar <nivedita@alum.mit.edu>,
	hpa@zytor.com, Jiri Slaby <jslaby@suse.cz>,
	x86@kernel.org, David Rientjes <rientjes@google.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Joerg Roedel <jroedel@suse.de>, Kees Cook <keescook@chromium.org>,
	Cfir Cohen <cfir@google.com>,
	linux-coco@lists.linux.dev, Andy Lutomirski <luto@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Juergen Gross <jgross@suse.com>, Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <seanjc@google.com>,
	linux-kernel@vger.kernel.org,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Erdem Aktas <erdemaktas@google.com>
Subject: Re: [PATCH v3 4/7] x86/sev-es: Run #VC handler in plain IRQ state
Date: Tue, 8 Jun 2021 15:25:51 +0200	[thread overview]
Message-ID: <YL9v38J0JC5FrZnM@8bytes.org> (raw)
In-Reply-To: <YL9bd2hx/y9oD6x/@hirez.programming.kicks-ass.net>

Hi Peter,

On Tue, Jun 08, 2021 at 01:58:47PM +0200, Peter Zijlstra wrote:
> So #VC cannot happen with IRQs disabled?
> 
> 	raw_spin_lock_irq(&my_lock);
> 	<#VC>
> 		raw_spin_lock_irqsave(&my_lock); // whoopsie
> 
> Every exception that can happen with IRQs disabled must be NMI like.
> 
> Again, what you seem to want is to split the handler in a from-user and
> from-kernel way, just like we did with #DB and MCE. See how
> exc_debug_user() is IRQ-like and can send signals, while
> exc_debug_kernel() is NMI like and can not.

You are right, thanks for pointing this out. I replaced that patch by
one implementing the split in a from-user and from-kernel part. Initial
testing looks good, will send it out later this week.

Thanks,

	Joerg

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  reply	other threads:[~2021-06-08 13:25 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08  9:54 [PATCH v3 0/7] x86/sev-es: Fixes for SEV-ES Guest Support Joerg Roedel
2021-06-08  9:54 ` Joerg Roedel
2021-06-08  9:54 ` [PATCH v3 1/7] x86/ioremap: Map efi_mem_reserve() memory as encrypted for SEV Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel
2021-06-08 15:26   ` [tip: x86/urgent] x86/ioremap: Map EFI-reserved " tip-bot2 for Tom Lendacky
2021-06-08  9:54 ` [PATCH v3 2/7] x86/sev-es: Fix error message in runtime #VC handler Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel
2021-06-08  9:54 ` [PATCH v3 3/7] x86/sev-es: Disable IRQs while GHCB is active Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel
2021-06-08  9:54 ` [PATCH v3 4/7] x86/sev-es: Run #VC handler in plain IRQ state Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel
2021-06-08 11:58   ` Peter Zijlstra
2021-06-08 11:58     ` Peter Zijlstra
2021-06-08 13:25     ` Joerg Roedel [this message]
2021-06-08 13:25       ` Joerg Roedel
2021-06-08  9:54 ` [PATCH v3 5/7] x86/insn-eval: Make 0 a valid RIP for insn_get_effective_ip() Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel
2021-06-08  9:54 ` [PATCH v3 6/7] x86/insn: Extend error reporting from insn_fetch_from_user[_inatomic]() Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel
2021-06-08  9:54 ` [PATCH v3 7/7] x86/sev-es: Propagate #GP if getting linear instruction address failed Joerg Roedel
2021-06-08  9:54   ` Joerg Roedel

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