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BACKPORT: FROMGIT: KVM: arm64: Trap host SVE accesses when the FPSIMD state is dirty

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ZCR_EL2 controls the upper bound for ZCR_EL1, and is set to
a potentially lower limit when the guest uses SVE. In order
to restore the SVE state on the EL1 host, we must first
reset ZCR_EL2 to its original value.

To make it as lazy as possible on the EL1 host side, set
the SVE trapping in place when exiting from the guest.
On the first EL1 access to SVE, ZCR_EL2 will be restored
to its full glory.

Suggested-by: Andrew Scull <ascull@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit beed09067b428a7e84a53b05c1de1f93c8460e91
 git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next)
[will: Fixed trivial conflicts with host stage-2 series]
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 178098380
Test: atest VirtualizationHostTestCases on an EL2-enabled device
Change-Id: I4e43e3ea710f105fe15b08825678109ac5ee2b78
This commit is contained in:
Marc Zyngier
2021-03-17 16:50:39 +00:00
committed by Quentin Perret
parent 507e10616c
commit 194fd166b5
2 changed files with 11 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/kvm/hyp/nvhe/hyp-main.c
View File

@@ -241,6 +241,10 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
case ESR_ELx_EC_SMC64:
handle_host_smc(host_ctxt);
break;
case ESR_ELx_EC_SVE:
sve_cond_update_zcr_vq(ZCR_ELx_LEN_MASK, SYS_ZCR_EL2);
sysreg_clear_set(cptr_el2, CPTR_EL2_TZ, 0);
break;
case ESR_ELx_EC_IABT_LOW:
fallthrough;
case ESR_ELx_EC_DABT_LOW:

9
arch/arm64/kvm/hyp/nvhe/switch.c
View File

@@ -70,7 +70,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
static void __deactivate_traps(struct kvm_vcpu *vcpu)
{
extern char __kvm_hyp_host_vector[];
u64 mdcr_el2;
u64 mdcr_el2, cptr;
___deactivate_traps(vcpu);
@@ -101,7 +101,12 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
write_sysreg(mdcr_el2, mdcr_el2);
write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
cptr = CPTR_EL2_DEFAULT;
if (vcpu_has_sve(vcpu) && (vcpu->arch.flags & KVM_ARM64_FP_ENABLED))
cptr |= CPTR_EL2_TZ;
write_sysreg(cptr, cptr_el2);
write_sysreg(__kvm_hyp_host_vector, vbar_el2);
}