From: James Hogan <james.hogan@imgtec.com>
To: linux-mips@linux-mips.org
Cc: "James Hogan" <james.hogan@imgtec.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Ralf Baechle" <ralf@linux-mips.org>,
kvm@vger.kernel.org
Subject: [PATCH 1/3] KVM: MIPS: Fix lazy user ASID regenerate for SMP
Date: Tue, 25 Oct 2016 16:08:19 +0100 [thread overview]
Message-ID: <26798303b5e56962d2afcdbf878fc7a85f99ba98.1477320903.git-series.james.hogan@imgtec.com> (raw)
Message-ID: <20161025150819.SyT7kHAayjAVjJpgp_CJWWxVygbsHnrdHU1l5wXXnDs@z> (raw)
In-Reply-To: <cover.c0ced53ae71e1272ec1aaa16007e9eebb1c0eac6.1477320903.git-series.james.hogan@imgtec.com>
kvm_mips_check_asids() runs before entering the guest and performs lazy
regeneration of host ASID for guest usermode, using last_user_gasid to
track the last guest ASID in the VCPU that was used by guest usermode on
any host CPU.
last_user_gasid is reset after performing the lazy ASID regeneration on
the current CPU, and by kvm_arch_vcpu_load() if the host ASID for guest
usermode is regenerated due to staleness (to cancel outstanding lazy
ASID regenerations). Unfortunately neither case handles SMP hosts
correctly:
- When the lazy ASID regeneration is performed it should apply to all
CPUs (as last_user_gasid does), so reset the ASID on other CPUs to
zero to trigger regeneration when the VCPU is next loaded on those
CPUs.
- When the ASID is found to be stale on the current CPU, we should not
cancel lazy ASID regenerations globally, so drop the reset of
last_user_gasid altogether here.
Both cases would require a guest ASID change and two host CPU migrations
(and in the latter case one of the CPUs to start a new ASID cycle)
before guest usermode could potentially access stale user pages from a
previously running ASID in the same VCPU.
Fixes: 25b08c7fb0e4 ("KVM: MIPS: Invalidate TLB by regenerating ASIDs")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
---
arch/mips/kvm/mips.c | 5 ++++-
arch/mips/kvm/mmu.c | 4 ----
2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 622037d851a3..06a60b19acfb 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -426,7 +426,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
static void kvm_mips_check_asids(struct kvm_vcpu *vcpu)
{
struct mips_coproc *cop0 = vcpu->arch.cop0;
- int cpu = smp_processor_id();
+ int i, cpu = smp_processor_id();
unsigned int gasid;
/*
@@ -442,6 +442,9 @@ static void kvm_mips_check_asids(struct kvm_vcpu *vcpu)
vcpu);
vcpu->arch.guest_user_asid[cpu] =
vcpu->arch.guest_user_mm.context.asid[cpu];
+ for_each_possible_cpu(i)
+ if (i != cpu)
+ vcpu->arch.guest_user_asid[cpu] = 0;
vcpu->arch.last_user_gasid = gasid;
}
}
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 03883ba806e2..3b677c851be0 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -260,13 +260,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if ((vcpu->arch.guest_user_asid[cpu] ^ asid_cache(cpu)) &
asid_version_mask(cpu)) {
- u32 gasid = kvm_read_c0_guest_entryhi(vcpu->arch.cop0) &
- KVM_ENTRYHI_ASID;
-
kvm_get_new_mmu_context(&vcpu->arch.guest_user_mm, cpu, vcpu);
vcpu->arch.guest_user_asid[cpu] =
vcpu->arch.guest_user_mm.context.asid[cpu];
- vcpu->arch.last_user_gasid = gasid;
newasid++;
kvm_debug("[%d]: cpu_context: %#lx\n", cpu,
--
git-series 0.8.10
next prev parent reply other threads:[~2016-10-25 15:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-25 15:08 [PATCH 0/3] KVM: MIPS: Miscellaneous 4.9 fixes James Hogan
2016-10-25 15:08 ` James Hogan
2016-10-25 15:08 ` James Hogan [this message]
2016-10-25 15:08 ` [PATCH 1/3] KVM: MIPS: Fix lazy user ASID regenerate for SMP James Hogan
2016-10-25 15:11 ` [PATCH 2/3] KVM: MIPS: Make ERET handle ERL before EXL James Hogan
2016-10-25 15:11 ` James Hogan
2016-10-25 15:11 ` [PATCH 3/3] KVM: MIPS: Precalculate MMIO load resume PC James Hogan
2016-10-25 15:11 ` James Hogan
2016-10-25 15:57 ` [PATCH 0/3] KVM: MIPS: Miscellaneous 4.9 fixes Paolo Bonzini
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=26798303b5e56962d2afcdbf878fc7a85f99ba98.1477320903.git-series.james.hogan@imgtec.com \
--to=james.hogan@imgtec.com \
--cc=kvm@vger.kernel.org \
--cc=linux-mips@linux-mips.org \
--cc=pbonzini@redhat.com \
--cc=ralf@linux-mips.org \
--cc=rkrcmar@redhat.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).