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From: Andrew Jones <drjones@redhat.com>
To: Alexander Graf <graf@amazon.com>
Cc: Anup Patel <Anup.Patel@wdc.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Paolo Bonzini <pbonzini@redhat.com>, Radim K <rkrcmar@redhat.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Atish Patra <Atish.Patra@wdc.com>,
	Alistair Francis <Alistair.Francis@wdc.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Christoph Hellwig <hch@infradead.org>,
	Anup Patel <anup@brainfault.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 10/20] RISC-V: KVM: Handle MMIO exits for VCPU
Date: Thu, 22 Aug 2019 14:21:57 +0200	[thread overview]
Message-ID: <20190822122157.qy3e4rhxthfustn2@kamzik.brq.redhat.com> (raw)
In-Reply-To: <13cf8e10-3f54-a50a-0796-ecb2da4577d2@amazon.com>

On Thu, Aug 22, 2019 at 02:10:48PM +0200, Alexander Graf wrote:
> On 22.08.19 10:44, Anup Patel wrote:
...
> > +static int emulate_load(struct kvm_vcpu *vcpu, struct kvm_run *run,
> > +			unsigned long fault_addr)
...
> > +	/* Exit to userspace for MMIO emulation */
> > +	vcpu->stat.mmio_exit_user++;
> > +	run->exit_reason = KVM_EXIT_MMIO;
> > +	run->mmio.is_write = false;
> > +	run->mmio.phys_addr = fault_addr;
> > +	run->mmio.len = len;
> > +
> > +	/* Move to next instruction */
> > +	vcpu->arch.guest_context.sepc += INSN_LEN(insn);
> 
> Doesn't that make more sense on the reentry path? What if you want to inject
> an MCE on access to unmapped addresses from user space?
>

I agree. See commit 0d640732dbeb for arm's justification for moving
the instruction skip. But also see

https://patchwork.kernel.org/patch/11109063/

for a needed fix to avoid skipping the instructions multiple times.
It looks like riscv's KVM_RUN ioctl would be vulnerable to that as
well.

Thanks,
drew

  reply	other threads:[~2019-08-22 12:22 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-22  8:42 [PATCH v5 00/20] KVM RISC-V Support Anup Patel
2019-08-22  8:42 ` [PATCH v5 01/20] KVM: RISC-V: Add KVM_REG_RISCV for ONE_REG interface Anup Patel
2019-08-22  8:42 ` [PATCH v5 02/20] RISC-V: Add bitmap reprensenting ISA features common across CPUs Anup Patel
2019-08-22  8:43 ` [PATCH v5 03/20] RISC-V: Export few kernel symbols Anup Patel
2019-08-22  8:43 ` [PATCH v5 04/20] RISC-V: Add hypervisor extension related CSR defines Anup Patel
2019-08-22  8:43 ` [PATCH v5 05/20] RISC-V: Add initial skeletal KVM support Anup Patel
2019-08-22  8:43 ` [PATCH v5 06/20] RISC-V: KVM: Implement VCPU create, init and destroy functions Anup Patel
2019-08-22  8:44 ` [PATCH v5 07/20] RISC-V: KVM: Implement VCPU interrupts and requests handling Anup Patel
2019-08-22  8:44 ` [PATCH v5 08/20] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls Anup Patel
2019-08-22 12:01   ` Alexander Graf
2019-08-22 14:00     ` Anup Patel
2019-08-22 14:12       ` Alexander Graf
2019-08-23 11:20         ` Anup Patel
2019-08-23 11:42           ` Graf (AWS), Alexander
2019-08-22 14:05     ` Anup Patel
2019-08-22  8:44 ` [PATCH v5 09/20] RISC-V: KVM: Implement VCPU world-switch Anup Patel
2019-08-22  8:44 ` [PATCH v5 10/20] RISC-V: KVM: Handle MMIO exits for VCPU Anup Patel
2019-08-22 12:10   ` Alexander Graf
2019-08-22 12:21     ` Andrew Jones [this message]
2019-08-22 12:27     ` Anup Patel
2019-08-22 12:14   ` Alexander Graf
2019-08-22 12:33     ` Anup Patel
2019-08-22 13:25       ` Alexander Graf
2019-08-22 13:55         ` Anup Patel
2019-08-22  8:45 ` [PATCH v5 11/20] RISC-V: KVM: Handle WFI " Anup Patel
2019-08-22 12:19   ` Alexander Graf
2019-08-22 12:50     ` Anup Patel
2019-08-22  8:45 ` [PATCH v5 12/20] RISC-V: KVM: Implement VMID allocator Anup Patel
2019-08-22  8:45 ` [PATCH v5 13/20] RISC-V: KVM: Implement stage2 page table programming Anup Patel
2019-08-22 12:28   ` Alexander Graf
2019-08-22 12:38     ` Anup Patel
2019-08-22 13:27       ` Alexander Graf
2019-08-22 13:58         ` Anup Patel
2019-08-22 14:09           ` Alexander Graf
2019-08-23 11:21             ` Anup Patel
2019-08-22  8:45 ` [PATCH v5 14/20] RISC-V: KVM: Implement MMU notifiers Anup Patel
2019-08-22  8:46 ` [PATCH v5 15/20] RISC-V: KVM: Add timer functionality Anup Patel
2019-08-23  7:52   ` Alexander Graf
2019-08-23 11:04     ` Anup Patel
2019-08-23 11:33       ` Graf (AWS), Alexander
2019-08-23 11:46         ` Anup Patel
2019-08-23 11:49           ` Alexander Graf
2019-08-23 12:11             ` Anup Patel
2019-08-23 12:25               ` Alexander Graf
2019-08-22  8:46 ` [PATCH v5 16/20] RISC-V: KVM: FP lazy save/restore Anup Patel
2019-08-22  8:46 ` [PATCH v5 17/20] RISC-V: KVM: Implement ONE REG interface for FP registers Anup Patel
2019-08-22  8:46 ` [PATCH v5 18/20] RISC-V: KVM: Add SBI v0.1 support Anup Patel
2019-08-23  8:04   ` Alexander Graf
2019-08-23 11:17     ` Anup Patel
2019-08-23 11:38       ` Graf (AWS), Alexander
2019-08-23 12:00         ` Anup Patel
2019-08-23 12:19           ` Alexander Graf
2019-08-23 12:28             ` Anup Patel
2019-08-22  8:47 ` [PATCH v5 19/20] RISC-V: Enable VIRTIO drivers in RV64 and RV32 defconfig Anup Patel
2019-08-22  8:47 ` [PATCH v5 20/20] RISC-V: KVM: Add MAINTAINERS entry Anup Patel
2019-08-23  8:08 ` [PATCH v5 00/20] KVM RISC-V Support Alexander Graf
2019-08-23 11:25   ` Anup Patel
2019-08-23 11:44     ` Graf (AWS), Alexander
2019-08-23 12:10       ` Paolo Bonzini
2019-08-23 12:19         ` Anup Patel
2019-08-23 12:28           ` Alexander Graf

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