From: Marc Zyngier <maz@kernel.org>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Andre Przywara <andre.przywara@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
Jintack Lim <jintack@cs.columbia.edu>,
Haibo Xu <haibo.xu@linaro.org>,
Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH v5 14/69] KVM: arm64: nv: Support virtual EL2 exceptions
Date: Wed, 26 Jan 2022 20:32:39 +0000 [thread overview]
Message-ID: <875yq66xw8.wl-maz@kernel.org> (raw)
In-Reply-To: <YebklBdMSwOplyrJ@shell.armlinux.org.uk>
On Tue, 18 Jan 2022 16:02:28 +0000,
"Russell King (Oracle)" <linux@armlinux.org.uk> wrote:
>
> On Mon, Nov 29, 2021 at 08:00:55PM +0000, Marc Zyngier wrote:
> > From: Jintack Lim <jintack.lim@linaro.org>
> >
> > Support injecting exceptions and performing exception returns to and
> > from virtual EL2. This must be done entirely in software except when
> > taking an exception from vEL0 to vEL2 when the virtual HCR_EL2.{E2H,TGE}
> > == {1,1} (a VHE guest hypervisor).
> >
> > Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
> > Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
> > [maz: switch to common exception injection framework]
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
> > ---
> ...
> > +void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu)
> > +{
> > + u64 spsr, elr, mode;
> > + bool direct_eret;
> > +
> > + /*
> > + * Going through the whole put/load motions is a waste of time
> > + * if this is a VHE guest hypervisor returning to its own
> > + * userspace, or the hypervisor performing a local exception
> > + * return. No need to save/restore registers, no need to
> > + * switch S2 MMU. Just do the canonical ERET.
> > + */
> > + spsr = vcpu_read_sys_reg(vcpu, SPSR_EL2);
> > + mode = spsr & (PSR_MODE_MASK | PSR_MODE32_BIT);
> > +
> > + direct_eret = (mode == PSR_MODE_EL0t &&
> > + vcpu_el2_e2h_is_set(vcpu) &&
> > + vcpu_el2_tge_is_set(vcpu));
> > + direct_eret |= (mode == PSR_MODE_EL2h || mode == PSR_MODE_EL2t);
>
> There are excessive parens on the RHS of the above two.
I guess this is my personal taste, and this is the kind of cosmetic
things that help me reason about the code. Some people use syntax
highlighting, I use bracketing. I don't think this really matters in
the grand scheme of things.
[...]
> > +/*
> > + * Emulate taking an exception to EL2.
> > + * See ARM ARM J8.1.2 AArch64.TakeException()
> > + */
> > +static int kvm_inject_nested(struct kvm_vcpu *vcpu, u64 esr_el2,
> > + enum exception_type type)
> > +{
> > + u64 pstate, mode;
> > + bool direct_inject;
> > +
> > + if (!nested_virt_in_use(vcpu)) {
> > + kvm_err("Unexpected call to %s for the non-nesting configuration\n",
> > + __func__);
>
> Too much indentation. I'm guessing this "unexpected" condition isn't
> something that can be caused by a rogue guest? If it can, doesn't this
> need to be rate limited?
If we end-up here, this is very much a hypervisor logic bug.
[...]
> > +
> > + /* If not nesting, EL1 is the only possible exception target */
> > + if (likely(!nested_virt_in_use(vcpu))) {
> > + vcpu->arch.flags |= KVM_ARM64_EXCEPT_AA64_EL1;
> > + return;
> > + }
> > +
> > + /*
> > + * With NV, we need to pick between EL1 and EL2. Note that we
> > + * never deal with a nesting exception here, hence never
> > + * changing context, and the exception itself can be delayed
> > + * until the next entry.
> > + */
> > + switch(*vcpu_cpsr(vcpu) & PSR_MODE_MASK) {
> > + case PSR_MODE_EL2h:
> > + case PSR_MODE_EL2t:
> > + vcpu->arch.flags |= KVM_ARM64_EXCEPT_AA64_EL2;
> > + break;
> > + case PSR_MODE_EL1h:
> > + case PSR_MODE_EL1t:
> > + vcpu->arch.flags |= KVM_ARM64_EXCEPT_AA64_EL1;
> > + break;
> > + case PSR_MODE_EL0t:
> > + if (vcpu_el2_tge_is_set(vcpu) & HCR_TGE)
> > + vcpu->arch.flags |= KVM_ARM64_EXCEPT_AA64_EL2;
> > + else
> > + vcpu->arch.flags |= KVM_ARM64_EXCEPT_AA64_EL1;
> > + break;
> > + default:
> > + BUG();
>
> Is taking out the host really appropriate here? Is this something a
> rogue guest could trigger?
This switch is supposed to cover all the NS exception levels, in
either stack configuration. If we suddenly find ourselves with a
non-architectural state, we have horribly messed up. And no, a guest
shouldn't be able to affect this. If it can, that's even more of a
reason to take everything down ASAP.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2022-01-26 20:32 UTC|newest]
Thread overview: 139+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-29 20:00 [PATCH v5 00/69] KVM: arm64: ARMv8.3/8.4 Nested Virtualization support Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 01/69] KVM: arm64: Save PSTATE early on exit Marc Zyngier
2022-01-17 15:36 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 02/69] KVM: arm64: Move pkvm's special 32bit handling into a generic infrastructure Marc Zyngier
2022-01-17 15:34 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 03/69] KVM: arm64: Add minimal handling for the ARMv8.7 PMU Marc Zyngier
2022-01-17 15:40 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 04/69] KVM: arm64: Rework kvm_pgtable initialisation Marc Zyngier
2022-01-17 15:43 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 05/69] KVM: arm64: Allow preservation of the S2 SW bits Marc Zyngier
2022-01-13 12:12 ` Alexandru Elisei
2022-01-13 13:14 ` Marc Zyngier
2022-01-17 15:51 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 06/69] arm64: Add ARM64_HAS_NESTED_VIRT cpufeature Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 07/69] KVM: arm64: nv: Introduce nested virtualization VCPU feature Marc Zyngier
2021-12-20 6:45 ` Ganapatrao Kulkarni
2022-01-13 14:10 ` Alexandru Elisei
2022-01-13 14:24 ` Marc Zyngier
2022-01-17 16:57 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 08/69] KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set Marc Zyngier
2022-01-07 21:54 ` Chase Conklin
2022-01-27 12:42 ` Marc Zyngier
2022-01-17 17:06 ` Russell King (Oracle)
2022-01-27 12:43 ` Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 09/69] KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x Marc Zyngier
2022-01-17 17:07 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 10/69] KVM: arm64: nv: Add EL2 system registers to vcpu context Marc Zyngier
2022-01-17 17:14 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 11/69] KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state Marc Zyngier
2022-01-14 17:42 ` Alexandru Elisei
2022-01-15 12:19 ` Marc Zyngier
2022-01-17 10:19 ` Alexandru Elisei
2022-01-18 15:45 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 12/69] KVM: arm64: nv: Handle HCR_EL2.NV system register traps Marc Zyngier
2022-01-17 11:31 ` Alexandru Elisei
2022-01-26 16:08 ` Marc Zyngier
2022-01-18 15:51 ` Russell King (Oracle)
2022-01-26 16:01 ` Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 13/69] KVM: arm64: nv: Reset VMPIDR_EL2 and VPIDR_EL2 to sane values Marc Zyngier
2022-01-18 15:52 ` Russell King (Oracle)
2021-11-29 20:00 ` [PATCH v5 14/69] KVM: arm64: nv: Support virtual EL2 exceptions Marc Zyngier
2021-12-20 6:57 ` Ganapatrao Kulkarni
2022-01-18 14:11 ` Alexandru Elisei
2022-01-26 20:11 ` Marc Zyngier
2022-01-18 16:02 ` Russell King (Oracle)
2022-01-26 20:32 ` Marc Zyngier [this message]
2022-01-20 13:58 ` Alexandru Elisei
2022-01-27 11:08 ` Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 15/69] KVM: arm64: nv: Inject HVC exceptions to the virtual EL2 Marc Zyngier
2022-01-18 16:04 ` Russell King (Oracle)
2022-01-18 16:35 ` Alexandru Elisei
2021-11-29 20:00 ` [PATCH v5 16/69] KVM: arm64: nv: Handle trapped ERET from " Marc Zyngier
2022-01-18 16:05 ` Russell King (Oracle)
2022-01-18 16:36 ` Alexandru Elisei
2022-01-27 11:50 ` Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 17/69] KVM: arm64: nv: Add non-VHE-EL2->EL1 translation helpers Marc Zyngier
2022-01-20 11:52 ` Alexandru Elisei
2022-01-27 17:22 ` Marc Zyngier
2021-11-29 20:00 ` [PATCH v5 18/69] KVM: arm64: nv: Handle virtual EL2 registers in vcpu_read/write_sys_reg() Marc Zyngier
2021-12-20 7:04 ` Ganapatrao Kulkarni
2021-12-20 9:10 ` Marc Zyngier
2021-12-21 7:12 ` Ganapatrao Kulkarni
2021-12-21 8:39 ` Marc Zyngier
2021-12-21 10:12 ` Ganapatrao Kulkarni
2022-01-20 15:12 ` Alexandru Elisei
2021-11-29 20:01 ` [PATCH v5 19/69] KVM: arm64: nv: Handle SPSR_EL2 specially Marc Zyngier
2022-01-20 16:28 ` Alexandru Elisei
2021-11-29 20:01 ` [PATCH v5 20/69] KVM: arm64: nv: Handle HCR_EL2.E2H specially Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 21/69] KVM: arm64: nv: Save/Restore vEL2 sysregs Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 22/69] KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 23/69] KVM: arm64: nv: Trap EL1 VM register accesses in virtual EL2 Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 24/69] KVM: arm64: nv: Trap SPSR_EL1, ELR_EL1 and VBAR_EL1 from " Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 25/69] KVM: arm64: nv: Trap CPACR_EL1 access in " Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 26/69] KVM: arm64: nv: Handle PSCI call via smc from the guest Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 27/69] KVM: arm64: nv: Respect virtual HCR_EL2.TWX setting Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 28/69] KVM: arm64: nv: Respect virtual CPTR_EL2.{TFP,FPEN} settings Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 29/69] KVM: arm64: nv: Respect the virtual HCR_EL2.NV bit setting Marc Zyngier
2021-12-20 7:11 ` Ganapatrao Kulkarni
2021-12-20 9:18 ` Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 30/69] KVM: arm64: nv: Respect virtual HCR_EL2.TVM and TRVM settings Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 31/69] KVM: arm64: nv: Respect the virtual HCR_EL2.NV1 bit setting Marc Zyngier
2021-12-20 7:18 ` Ganapatrao Kulkarni
2021-12-20 9:39 ` Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 32/69] KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2 Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 33/69] KVM: arm64: nv: Forward debug traps to the nested guest Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 34/69] KVM: arm64: nv: Configure HCR_EL2 for nested virtualization Marc Zyngier
2022-01-04 8:53 ` Ganapatrao Kulkarni
2022-01-04 9:39 ` Marc Zyngier
2022-01-04 9:53 ` Ganapatrao Kulkarni
2021-11-29 20:01 ` [PATCH v5 35/69] KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 36/69] KVM: arm64: nv: Filter out unsupported features from ID regs Marc Zyngier
2021-12-20 7:26 ` Ganapatrao Kulkarni
2021-12-20 9:56 ` Marc Zyngier
2021-12-21 6:03 ` Ganapatrao Kulkarni
2021-12-21 9:10 ` Marc Zyngier
2021-12-21 10:07 ` Ganapatrao Kulkarni
2022-01-21 11:33 ` Ganapatrao Kulkarni
2022-01-27 13:04 ` Marc Zyngier
2022-01-04 10:24 ` Ganapatrao Kulkarni
2021-11-29 20:01 ` [PATCH v5 37/69] KVM: arm64: nv: Hide RAS from nested guests Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 38/69] KVM: arm64: nv: Support multiple nested Stage-2 mmu structures Marc Zyngier
2022-01-18 11:24 ` Ganapatrao Kulkarni
2022-01-27 11:50 ` Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 39/69] KVM: arm64: nv: Implement nested Stage-2 page table walk logic Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 40/69] KVM: arm64: nv: Handle shadow stage 2 page faults Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 41/69] KVM: arm64: nv: Restrict S2 RD/WR permissions to match the guest's Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 42/69] KVM: arm64: nv: Unmap/flush shadow stage 2 page tables Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 43/69] KVM: arm64: nv: Introduce sys_reg_desc.forward_trap Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 44/69] KVM: arm64: nv: Set a handler for the system instruction traps Marc Zyngier
2022-01-18 11:29 ` Ganapatrao Kulkarni
2021-11-29 20:01 ` [PATCH v5 45/69] KVM: arm64: nv: Trap and emulate AT instructions from virtual EL2 Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 46/69] KVM: arm64: nv: Trap and emulate TLBI " Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 47/69] KVM: arm64: nv: Fold guest's HCR_EL2 configuration into the host's Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 48/69] KVM: arm64: nv: arch_timer: Support hyp timer emulation Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 49/69] KVM: arm64: nv: Add handling of EL2-specific timer registers Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 50/69] KVM: arm64: nv: Load timer before the GIC Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 51/69] KVM: arm64: nv: Nested GICv3 Support Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 52/69] KVM: arm64: nv: Don't load the GICv4 context on entering a nested guest Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 53/69] KVM: arm64: nv: vgic: Emulate the HW bit in software Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 54/69] KVM: arm64: nv: vgic: Allow userland to set VGIC maintenance IRQ Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 55/69] KVM: arm64: nv: Implement maintenance interrupt forwarding Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 56/69] KVM: arm64: nv: Add nested GICv3 tracepoints Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 57/69] KVM: arm64: nv: Allow userspace to request KVM_ARM_VCPU_NESTED_VIRT Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 58/69] KVM: arm64: nv: Add handling of ARMv8.4-TTL TLB invalidation Marc Zyngier
2022-01-18 11:35 ` Ganapatrao Kulkarni
2021-11-29 20:01 ` [PATCH v5 59/69] KVM: arm64: nv: Invalidate TLBs based on shadow S2 TTL-like information Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 60/69] KVM: arm64: nv: Tag shadow S2 entries with nested level Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 61/69] KVM: arm64: nv: Add include containing the VNCR_EL2 offsets Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 62/69] KVM: arm64: nv: Map VNCR-capable registers to a separate page Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 63/69] KVM: arm64: nv: Move nested vgic state into the sysreg file Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 64/69] KVM: arm64: Add ARMv8.4 Enhanced Nested Virt cpufeature Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 65/69] KVM: arm64: nv: Sync nested timer state with ARMv8.4 Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 66/69] KVM: arm64: nv: Allocate VNCR page when required Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 67/69] KVM: arm64: nv: Enable ARMv8.4-NV support Marc Zyngier
2022-01-18 11:50 ` Ganapatrao Kulkarni
2022-01-27 11:48 ` Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 68/69] KVM: arm64: nv: Fast-track 'InHost' exception returns Marc Zyngier
2021-11-29 20:01 ` [PATCH v5 69/69] KVM: arm64: nv: Fast-track EL1 TLBIs for VHE guests Marc Zyngier
2021-12-16 17:19 ` (subset) [PATCH v5 00/69] KVM: arm64: ARMv8.3/8.4 Nested Virtualization support Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=875yq66xw8.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=alexandru.elisei@arm.com \
--cc=andre.przywara@arm.com \
--cc=christoffer.dall@arm.com \
--cc=gankulkarni@os.amperecomputing.com \
--cc=haibo.xu@linaro.org \
--cc=james.morse@arm.com \
--cc=jintack@cs.columbia.edu \
--cc=kernel-team@android.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux@armlinux.org.uk \
--cc=suzuki.poulose@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).