From: Mark Rutland <mark.rutland@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
Jintack Lim <jintack@cs.columbia.edu>,
Andre Przywara <andre.przywara@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
kvmarm@lists.cs.columbia.edu, Will Deacon <will@kernel.org>,
George Cherian <gcherian@marvell.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
"Zengtao \(B\)" <prime.zeng@hisilicon.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Dave Martin <Dave.Martin@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 26/26] KVM: arm64: Parametrize exception entry with a target EL
Date: Tue, 19 May 2020 11:44:57 +0100 [thread overview]
Message-ID: <20200519104457.GA19548@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20200422120050.3693593-27-maz@kernel.org>
On Wed, Apr 22, 2020 at 01:00:50PM +0100, Marc Zyngier wrote:
> We currently assume that an exception is delivered to EL1, always.
> Once we emulate EL2, this no longer will be the case. To prepare
> for this, add a target_mode parameter.
>
> While we're at it, merge the computing of the target PC and PSTATE in
> a single function that updates both PC and CPSR after saving their
> previous values in the corresponding ELR/SPSR. This ensures that they
> are updated in the correct order (a pretty common source of bugs...).
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/kvm/inject_fault.c | 75 ++++++++++++++++++-----------------
> 1 file changed, 38 insertions(+), 37 deletions(-)
>
> diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
> index d3ebf8bca4b89..3dbcbc839b9c3 100644
> --- a/arch/arm64/kvm/inject_fault.c
> +++ b/arch/arm64/kvm/inject_fault.c
> @@ -26,28 +26,12 @@ enum exception_type {
> except_type_serror = 0x180,
> };
>
> -static u64 get_except_vector(struct kvm_vcpu *vcpu, enum exception_type type)
> -{
> - u64 exc_offset;
> -
> - switch (*vcpu_cpsr(vcpu) & (PSR_MODE_MASK | PSR_MODE32_BIT)) {
> - case PSR_MODE_EL1t:
> - exc_offset = CURRENT_EL_SP_EL0_VECTOR;
> - break;
> - case PSR_MODE_EL1h:
> - exc_offset = CURRENT_EL_SP_ELx_VECTOR;
> - break;
> - case PSR_MODE_EL0t:
> - exc_offset = LOWER_EL_AArch64_VECTOR;
> - break;
> - default:
> - exc_offset = LOWER_EL_AArch32_VECTOR;
> - }
> -
> - return vcpu_read_sys_reg(vcpu, VBAR_EL1) + exc_offset + type;
> -}
> -
> /*
> + * This performs the exception entry at a given EL (@target_mode), stashing PC
> + * and PSTATE into ELR and SPSR respectively, and compute the new PC/PSTATE.
> + * The EL passed to this function *must* be a non-secure, privileged mode with
> + * bit 0 being set (PSTATE.SP == 1).
> + *
> * When an exception is taken, most PSTATE fields are left unchanged in the
> * handler. However, some are explicitly overridden (e.g. M[4:0]). Luckily all
> * of the inherited bits have the same position in the AArch64/AArch32 SPSR_ELx
> @@ -59,10 +43,35 @@ static u64 get_except_vector(struct kvm_vcpu *vcpu, enum exception_type type)
> * Here we manipulate the fields in order of the AArch64 SPSR_ELx layout, from
> * MSB to LSB.
> */
> -static unsigned long get_except64_pstate(struct kvm_vcpu *vcpu)
> +static void enter_exception(struct kvm_vcpu *vcpu, unsigned long target_mode,
> + enum exception_type type)
Since this is all for an AArch64 target, could we keep `64` in the name,
e.g enter_exception64? That'd mirror the callers below.
> {
> - unsigned long sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1);
> - unsigned long old, new;
> + unsigned long sctlr, vbar, old, new, mode;
> + u64 exc_offset;
> +
> + mode = *vcpu_cpsr(vcpu) & (PSR_MODE_MASK | PSR_MODE32_BIT);
> +
> + if (mode == target_mode)
> + exc_offset = CURRENT_EL_SP_ELx_VECTOR;
> + else if ((mode | 1) == target_mode)
> + exc_offset = CURRENT_EL_SP_EL0_VECTOR;
It would be nice if we could add a mnemonic for the `1` here, e.g.
PSR_MODE_SP0 or PSR_MODE_THREAD_BIT.
> + else if (!(mode & PSR_MODE32_BIT))
> + exc_offset = LOWER_EL_AArch64_VECTOR;
> + else
> + exc_offset = LOWER_EL_AArch32_VECTOR;
Other than the above, I couldn't think of a nicer way of writing thism
and AFAICT this is correct.
> +
> + switch (target_mode) {
> + case PSR_MODE_EL1h:
> + vbar = vcpu_read_sys_reg(vcpu, VBAR_EL1);
> + sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1);
> + vcpu_write_sys_reg(vcpu, *vcpu_pc(vcpu), ELR_EL1);
> + break;
> + default:
> + /* Don't do that */
> + BUG();
> + }
> +
> + *vcpu_pc(vcpu) = vbar + exc_offset + type;
>
> old = *vcpu_cpsr(vcpu);
> new = 0;
> @@ -105,9 +114,10 @@ static unsigned long get_except64_pstate(struct kvm_vcpu *vcpu)
> new |= PSR_I_BIT;
> new |= PSR_F_BIT;
>
> - new |= PSR_MODE_EL1h;
> + new |= target_mode;
As a heads-up, some of the other bits will need to change for an EL2
target (e.g. SPAN will depend on HCR_EL2.E2H), but as-is this this is
fine.
Regardless of the above comments:
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Mark.
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next prev parent reply other threads:[~2020-05-19 10:45 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 12:00 [PATCH 00/26] KVM: arm64: Preliminary NV patches Marc Zyngier
2020-04-22 12:00 ` [PATCH 01/26] KVM: arm64: Check advertised Stage-2 page size capability Marc Zyngier
2020-04-22 13:40 ` Suzuki K Poulose
2020-04-22 14:07 ` Marc Zyngier
2020-04-22 14:14 ` Suzuki K Poulose
2020-05-07 11:42 ` Alexandru Elisei
2020-04-22 12:00 ` [PATCH 02/26] KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h Marc Zyngier
2020-04-22 13:51 ` Suzuki K Poulose
2020-04-22 13:59 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 03/26] KVM: arm64: Factor out stage 2 page table data from struct kvm Marc Zyngier
2020-05-05 15:26 ` Andrew Scull
2020-05-05 16:32 ` Marc Zyngier
2020-05-05 17:23 ` Andrew Scull
2020-05-05 18:10 ` Marc Zyngier
2020-05-05 16:03 ` James Morse
2020-05-05 17:59 ` Marc Zyngier
2020-05-06 9:30 ` Marc Zyngier
2020-05-11 16:38 ` Alexandru Elisei
2020-05-12 11:17 ` James Morse
2020-05-12 15:47 ` Alexandru Elisei
2020-05-12 16:13 ` James Morse
2020-05-12 16:53 ` Alexandru Elisei
2020-05-27 8:41 ` Marc Zyngier
2020-05-27 8:45 ` Alexandru Elisei
2020-04-22 12:00 ` [PATCH 04/26] arm64: Detect the ARMv8.4 TTL feature Marc Zyngier
2020-04-27 15:55 ` Suzuki K Poulose
2020-04-22 12:00 ` [PATCH 05/26] arm64: Document SW reserved PTE/PMD bits in Stage-2 descriptors Marc Zyngier
2020-05-05 15:59 ` Andrew Scull
2020-05-06 9:39 ` Marc Zyngier
2020-05-06 10:11 ` Andrew Scull
2020-04-22 12:00 ` [PATCH 06/26] arm64: Add level-hinted TLB invalidation helper Marc Zyngier
2020-05-05 17:16 ` Andrew Scull
2020-05-06 8:05 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 07/26] KVM: arm64: Add a level hint to __kvm_tlb_flush_vmid_ipa Marc Zyngier
2020-05-07 15:08 ` Andrew Scull
2020-05-07 15:13 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 08/26] KVM: arm64: Use TTL hint in when invalidating stage-2 translations Marc Zyngier
2020-05-07 15:13 ` Andrew Scull
2020-05-12 12:04 ` James Morse
2020-05-13 9:06 ` Andrew Scull
2020-05-27 8:59 ` Marc Zyngier
2020-05-12 17:26 ` James Morse
2020-04-22 12:00 ` [PATCH 09/26] KVM: arm64: vgic-v3: Take cpu_if pointer directly instead of vcpu Marc Zyngier
2020-05-07 16:26 ` James Morse
2020-05-08 12:20 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 10/26] KVM: arm64: Refactor vcpu_{read,write}_sys_reg Marc Zyngier
2020-05-26 16:28 ` James Morse
2020-05-27 10:04 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 11/26] KVM: arm64: Add missing reset handlers for PMU emulation Marc Zyngier
2020-05-26 16:29 ` James Morse
2020-04-22 12:00 ` [PATCH 12/26] KVM: arm64: Move sysreg reset check to boot time Marc Zyngier
2020-04-22 12:00 ` [PATCH 13/26] KVM: arm64: Introduce accessor for ctxt->sys_reg Marc Zyngier
2020-04-22 12:00 ` [PATCH 14/26] KVM: arm64: hyp: Use ctxt_sys_reg/__vcpu_sys_reg instead of raw sys_regs access Marc Zyngier
2020-04-22 12:00 ` [PATCH 15/26] KVM: arm64: sve: Use __vcpu_sys_reg() " Marc Zyngier
2020-04-22 12:00 ` [PATCH 16/26] KVM: arm64: pauth: Use ctxt_sys_reg() " Marc Zyngier
2020-04-22 12:00 ` [PATCH 17/26] KVM: arm64: debug: " Marc Zyngier
2020-04-22 12:00 ` [PATCH 18/26] KVM: arm64: Don't use empty structures as CPU reset state Marc Zyngier
2020-04-24 4:07 ` Zenghui Yu
2020-04-24 7:45 ` Marc Zyngier
2020-04-28 1:34 ` Zengtao (B)
2020-04-22 12:00 ` [PATCH 19/26] KVM: arm64: Make struct kvm_regs userspace-only Marc Zyngier
2020-05-26 16:29 ` James Morse
2020-05-27 10:22 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 20/26] KVM: arm64: Move ELR_EL1 to the system register array Marc Zyngier
2020-05-26 16:29 ` James Morse
2020-05-27 10:36 ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 21/26] KVM: arm64: Move SP_EL1 " Marc Zyngier
2020-05-26 16:29 ` James Morse
2020-04-22 12:00 ` [PATCH 22/26] KVM: arm64: Disintegrate SPSR array Marc Zyngier
2020-05-26 16:30 ` James Morse
2020-04-22 12:00 ` [PATCH 23/26] KVM: arm64: Move SPSR_EL1 to the system register array Marc Zyngier
2020-05-26 16:30 ` James Morse
2020-04-22 12:00 ` [PATCH 24/26] KVM: arm64: timers: Rename kvm_timer_sync_hwstate to kvm_timer_sync_user Marc Zyngier
2020-04-22 12:00 ` [PATCH 25/26] KVM: arm64: timers: Move timer registers to the sys_regs file Marc Zyngier
2020-04-22 12:00 ` [PATCH 26/26] KVM: arm64: Parametrize exception entry with a target EL Marc Zyngier
2020-05-19 10:44 ` Mark Rutland [this message]
2020-05-27 9:34 ` Marc Zyngier
2020-05-27 14:41 ` Mark Rutland
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