[PATCH 24/25] KVM: arm64: Make FEAT_MOPS UNDEF if not advertised to the guest
Joey Gouly
joey.gouly at arm.com
Thu Jan 25 09:35:21 PST 2024
It's me again!
On Thu, Jan 25, 2024 at 04:25:38PM +0000, Joey Gouly wrote:
> On Mon, Jan 22, 2024 at 08:18:51PM +0000, Marc Zyngier wrote:
> > We unconditionally enable FEAT_MOPS, which is obviously wrong.
> >
> > So let's only do that when it is advertised to the guest.
> > Which means we need to rely on a per-vcpu HCRX_EL2 shadow register.
> >
> > Signed-off-by: Marc Zyngier <maz at kernel.org>
> > ---
> > arch/arm64/include/asm/kvm_arm.h | 4 +---
> > arch/arm64/include/asm/kvm_host.h | 1 +
> > arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +-
> > arch/arm64/kvm/sys_regs.c | 8 ++++++++
> > 4 files changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> > index 3c6f8ba1e479..a1769e415d72 100644
> > --- a/arch/arm64/include/asm/kvm_arm.h
> > +++ b/arch/arm64/include/asm/kvm_arm.h
> > @@ -102,9 +102,7 @@
> > #define HCR_HOST_NVHE_PROTECTED_FLAGS (HCR_HOST_NVHE_FLAGS | HCR_TSC)
> > #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
> >
> > -#define HCRX_GUEST_FLAGS \
> > - (HCRX_EL2_SMPME | HCRX_EL2_TCR2En | \
> > - (cpus_have_final_cap(ARM64_HAS_MOPS) ? (HCRX_EL2_MSCEn | HCRX_EL2_MCE2) : 0))
> > +#define HCRX_GUEST_FLAGS (HCRX_EL2_SMPME | HCRX_EL2_TCR2En)
> > #define HCRX_HOST_FLAGS (HCRX_EL2_MSCEn | HCRX_EL2_TCR2En)
> >
> > /* TCR_EL2 Registers bits */
> > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> > index fe5ed4bcded0..22343354db3e 100644
> > --- a/arch/arm64/include/asm/kvm_host.h
> > +++ b/arch/arm64/include/asm/kvm_host.h
> > @@ -584,6 +584,7 @@ struct kvm_vcpu_arch {
> >
> > /* Values of trap registers for the guest. */
> > u64 hcr_el2;
> > + u64 hcrx_el2;
> > u64 mdcr_el2;
> > u64 cptr_el2;
> >
> > diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> > index 2d5891518006..e3fcf8c4d5b4 100644
> > --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> > +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> > @@ -236,7 +236,7 @@ static inline void __activate_traps_common(struct kvm_vcpu *vcpu)
> > write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
> >
> > if (cpus_have_final_cap(ARM64_HAS_HCX)) {
> > - u64 hcrx = HCRX_GUEST_FLAGS;
> > + u64 hcrx = vcpu->arch.hcrx_el2;
> > if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)) {
> > u64 clr = 0, set = 0;
> >
> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index afe6975fcf5c..b7977e08e4ef 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -3952,6 +3952,14 @@ void kvm_init_sysreg(struct kvm_vcpu *vcpu)
> > if (!kvm_has_feat(kvm, ID_AA64ISAR0_EL1, TLB, OS))
> > vcpu->arch.hcr_el2 |= HCR_TTLBOS;
> >
> > + if (cpus_have_final_cap(ARM64_HAS_HCX)) {
> > + vcpu->arch.hcrx_el2 = HCRX_GUEST_FLAGS;
> > +
> > + if (kvm_has_feat(kern_hyp_va(vcpu->kvm),
>
> Not sure if the use of kern_hyp_va is intentional, seems out of place since we
> use the bare `kvm` variable everyone else.
My conclusion is that it's a mistake (kvm-arm.mode=nvhe):
[ 2707.523935] Unable to handle kernel paging request at virtual address 0000d34801b3fdb0
[ 2707.523945] Mem abort info:
[ 2707.523951] ESR = 0x0000000096000004
[ 2707.523957] EC = 0x25: DABT (current EL), IL = 32 bits
[ 2707.523966] SET = 0, FnV = 0
[ 2707.523973] EA = 0, S1PTW = 0
[ 2707.523980] FSC = 0x04: level 0 translation fault
[ 2707.523988] Data abort info:
[ 2707.523993] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 2707.524001] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 2707.524010] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 2707.524019] user pgtable: 4k pages, 48-bit VAs, pgdp=000000088341d000
[ 2707.524029] [0000d34801b3fdb0] pgd=0000000000000000, p4d=0000000000000000
[ 2707.524043] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[ 2707.524053] Modules linked in:
[ 2707.524060] CPU: 0 PID: 95 Comm: kvm-vcpu-0 Tainted: G T 6.8.0-rc1-asahi+ #4542 a70fa90dc88a9bc3f39943d7335081d8cc583f45
[ 2707.524076] Hardware name: FVP Base RevC (DT)
[ 2707.524083] pstate: 141402005 (nZcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 2707.524096] pc : kvm_init_sysreg+0x100/0x398
[ 2707.524106] lr : kvm_init_sysreg+0xd8/0x398
[ 2707.524116] sp : ffff8000808e3a60
[ 2707.524123] x29: ffff8000808e3a60 x28: ffff000802f0d640 x27: 0000000000000001
[ 2707.524141] x26: 0000000000000000 x25: ffff000802f30000 x24: 0000000000000000
[ 2707.524159] x23: ffff000800189100 x22: ffff000802f0d640 x21: ffff000801b3fbc8
[ 2707.524177] x20: ffff000802f30000 x19: ffff000801b3f000 x18: ffffffffffffffff
[ 2707.524195] x17: 0000000000000000 x16: 0000000000000000 x15: ffff8001008e36e7
[ 2707.524213] x14: 0000000000000000 x13: ffffd7c64c841608 x12: 0000000000000537
[ 2707.524230] x11: 00000000000001bd x10: ffffd7c64c899608 x9 : ffffd7c64c841608
[ 2707.524248] x8 : 00000000ffffefff x7 : ffffd7c64c899608 x6 : 0000000000000000
[ 2707.524266] x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000
[ 2707.524283] x2 : ffff000802f0d640 x1 : 0000000000004020 x0 : 0000d34801b3f000
[ 2707.524301] Call trace:
[ 2707.524306] kvm_init_sysreg+0x100/0x398
[ 2707.524316] kvm_arch_vcpu_run_pid_change+0xe8/0x3f4
[ 2707.524330] kvm_vcpu_ioctl+0x878/0x944
[ 2707.524341] __arm64_sys_ioctl+0x404/0xc68
Thanks,
Joey
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