RE: [PATCH 2/2] kvm: ppc: booke: check range page invalidation progress on page setup
-Original Message-
From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo
Bonzini
Sent: Monday, October 07, 2013 5:35 PM
To: Alexander Graf
Cc: Bhushan Bharat-R65777; Paul Mackerras; Wood Scott-B07421; kvm-
p...@vger.kernel.org; k...@vger.kernel.org mailing list; Bhushan
Bharat-R65777;
Gleb Natapov
Subject: Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation
progress
on page setup
Il 04/10/2013 15:38, Alexander Graf ha scritto:
On 07.08.2013, at 12:03, Bharat Bhushan wrote:
When the MM code is invalidating a range of pages, it calls the KVM
kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
kvm_unmap_hva_range(), which arranges to flush all the TLBs for guest
pages.
However, the Linux PTEs for the range being flushed are still valid at
that point. We are not supposed to establish any new references to pages
in the range until the ...range_end() notifier gets called.
The PPC-specific KVM code doesn't get any explicit notification of that;
instead, we are supposed to use mmu_notifier_retry() to test whether we
are or have been inside a range flush notifier pair while we have been
referencing a page.
This patch calls the mmu_notifier_retry() while mapping the guest
page to ensure we are not referencing a page when in range invalidation.
This call is inside a region locked with kvm-mmu_lock, which is the
same lock that is called by the KVM MMU notifier functions, thus
ensuring that no new notification can proceed while we are in the
locked region.
Signed-off-by: Bharat Bhushan bharat.bhus...@freescale.com
Acked-by: Alexander Graf ag...@suse.de
Gleb, Paolo, please queue for 3.12 directly.
Here is the backport. The second hunk has a nontrivial conflict, so
someone please give their {Tested,Reviewed,Compiled}-by.
{Compiled,Reviewed}-by: Bharat Bhushan bharat.bhus...@freescale.com
Thanks
-Bharat
Paolo
diff --git a/arch/powerpc/kvm/e500_mmu_host.c
b/arch/powerpc/kvm/e500_mmu_host.c
index 1c6a9d7..c65593a 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -332,6 +332,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
unsigned long hva;
int pfnmap = 0;
int tsize = BOOK3E_PAGESZ_4K;
+ int ret = 0;
+ unsigned long mmu_seq;
+ struct kvm *kvm = vcpu_e500-vcpu.kvm;
+
+ /* used to check for invalidations in progress */
+ mmu_seq = kvm-mmu_notifier_seq;
+ smp_rmb();
/*
* Translate guest physical to true physical, acquiring
@@ -449,6 +456,12 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
gvaddr = ~((tsize_pages PAGE_SHIFT) - 1);
}
+ spin_lock(kvm-mmu_lock);
+ if (mmu_notifier_retry(kvm, mmu_seq)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+
kvmppc_e500_ref_setup(ref, gtlbe, pfn);
kvmppc_e500_setup_stlbe(vcpu_e500-vcpu, gtlbe, tsize,
@@ -457,10 +470,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
/* Clear i-cache for new pages */
kvmppc_mmu_flush_icache(pfn);
+out:
+ spin_unlock(kvm-mmu_lock);
+
/* Drop refcount on page, so that mmu notifiers can clear it */
kvm_release_pfn_clean(pfn);
- return 0;
+ return ret;
}
/* XXX only map the one-one case, for now use TLB0 */
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Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation progress on page setup
Il 10/10/2013 10:32, Bhushan Bharat-R65777 ha scritto:
-Original Message-
From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo
Bonzini
Sent: Monday, October 07, 2013 5:35 PM
To: Alexander Graf
Cc: Bhushan Bharat-R65777; Paul Mackerras; Wood Scott-B07421; kvm-
p...@vger.kernel.org; k...@vger.kernel.org mailing list; Bhushan
Bharat-R65777;
Gleb Natapov
Subject: Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation
progress
on page setup
Il 04/10/2013 15:38, Alexander Graf ha scritto:
On 07.08.2013, at 12:03, Bharat Bhushan wrote:
When the MM code is invalidating a range of pages, it calls the KVM
kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
kvm_unmap_hva_range(), which arranges to flush all the TLBs for guest
pages.
However, the Linux PTEs for the range being flushed are still valid at
that point. We are not supposed to establish any new references to pages
in the range until the ...range_end() notifier gets called.
The PPC-specific KVM code doesn't get any explicit notification of that;
instead, we are supposed to use mmu_notifier_retry() to test whether we
are or have been inside a range flush notifier pair while we have been
referencing a page.
This patch calls the mmu_notifier_retry() while mapping the guest
page to ensure we are not referencing a page when in range invalidation.
This call is inside a region locked with kvm-mmu_lock, which is the
same lock that is called by the KVM MMU notifier functions, thus
ensuring that no new notification can proceed while we are in the
locked region.
Signed-off-by: Bharat Bhushan bharat.bhus...@freescale.com
Acked-by: Alexander Graf ag...@suse.de
Gleb, Paolo, please queue for 3.12 directly.
Here is the backport. The second hunk has a nontrivial conflict, so
someone please give their {Tested,Reviewed,Compiled}-by.
{Compiled,Reviewed}-by: Bharat Bhushan bharat.bhus...@freescale.com
Thanks, patch on its way to Linus.
Paolo
Thanks
-Bharat
Paolo
diff --git a/arch/powerpc/kvm/e500_mmu_host.c
b/arch/powerpc/kvm/e500_mmu_host.c
index 1c6a9d7..c65593a 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -332,6 +332,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
unsigned long hva;
int pfnmap = 0;
int tsize = BOOK3E_PAGESZ_4K;
+int ret = 0;
+unsigned long mmu_seq;
+struct kvm *kvm = vcpu_e500-vcpu.kvm;
+
+/* used to check for invalidations in progress */
+mmu_seq = kvm-mmu_notifier_seq;
+smp_rmb();
/*
* Translate guest physical to true physical, acquiring
@@ -449,6 +456,12 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
gvaddr = ~((tsize_pages PAGE_SHIFT) - 1);
}
+spin_lock(kvm-mmu_lock);
+if (mmu_notifier_retry(kvm, mmu_seq)) {
+ret = -EAGAIN;
+goto out;
+}
+
kvmppc_e500_ref_setup(ref, gtlbe, pfn);
kvmppc_e500_setup_stlbe(vcpu_e500-vcpu, gtlbe, tsize,
@@ -457,10 +470,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
/* Clear i-cache for new pages */
kvmppc_mmu_flush_icache(pfn);
+out:
+spin_unlock(kvm-mmu_lock);
+
/* Drop refcount on page, so that mmu notifiers can clear it */
kvm_release_pfn_clean(pfn);
-return 0;
+return ret;
}
/* XXX only map the one-one case, for now use TLB0 */
--
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Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation progress on page setup
Il 04/10/2013 15:38, Alexander Graf ha scritto:
On 07.08.2013, at 12:03, Bharat Bhushan wrote:
When the MM code is invalidating a range of pages, it calls the KVM
kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
kvm_unmap_hva_range(), which arranges to flush all the TLBs for guest pages.
However, the Linux PTEs for the range being flushed are still valid at
that point. We are not supposed to establish any new references to pages
in the range until the ...range_end() notifier gets called.
The PPC-specific KVM code doesn't get any explicit notification of that;
instead, we are supposed to use mmu_notifier_retry() to test whether we
are or have been inside a range flush notifier pair while we have been
referencing a page.
This patch calls the mmu_notifier_retry() while mapping the guest
page to ensure we are not referencing a page when in range invalidation.
This call is inside a region locked with kvm-mmu_lock, which is the
same lock that is called by the KVM MMU notifier functions, thus
ensuring that no new notification can proceed while we are in the
locked region.
Signed-off-by: Bharat Bhushan bharat.bhus...@freescale.com
Acked-by: Alexander Graf ag...@suse.de
Gleb, Paolo, please queue for 3.12 directly.
Here is the backport. The second hunk has a nontrivial conflict, so
someone please give their {Tested,Reviewed,Compiled}-by.
Paolo
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 1c6a9d7..c65593a 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -332,6 +332,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
unsigned long hva;
int pfnmap = 0;
int tsize = BOOK3E_PAGESZ_4K;
+ int ret = 0;
+ unsigned long mmu_seq;
+ struct kvm *kvm = vcpu_e500-vcpu.kvm;
+
+ /* used to check for invalidations in progress */
+ mmu_seq = kvm-mmu_notifier_seq;
+ smp_rmb();
/*
* Translate guest physical to true physical, acquiring
@@ -449,6 +456,12 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
gvaddr = ~((tsize_pages PAGE_SHIFT) - 1);
}
+ spin_lock(kvm-mmu_lock);
+ if (mmu_notifier_retry(kvm, mmu_seq)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+
kvmppc_e500_ref_setup(ref, gtlbe, pfn);
kvmppc_e500_setup_stlbe(vcpu_e500-vcpu, gtlbe, tsize,
@@ -457,10 +470,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
/* Clear i-cache for new pages */
kvmppc_mmu_flush_icache(pfn);
+out:
+ spin_unlock(kvm-mmu_lock);
+
/* Drop refcount on page, so that mmu notifiers can clear it */
kvm_release_pfn_clean(pfn);
- return 0;
+ return ret;
}
/* XXX only map the one-one case, for now use TLB0 */
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Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation progress on page setup
On 07.08.2013, at 12:03, Bharat Bhushan wrote:
When the MM code is invalidating a range of pages, it calls the KVM
kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
kvm_unmap_hva_range(), which arranges to flush all the TLBs for guest pages.
However, the Linux PTEs for the range being flushed are still valid at
that point. We are not supposed to establish any new references to pages
in the range until the ...range_end() notifier gets called.
The PPC-specific KVM code doesn't get any explicit notification of that;
instead, we are supposed to use mmu_notifier_retry() to test whether we
are or have been inside a range flush notifier pair while we have been
referencing a page.
This patch calls the mmu_notifier_retry() while mapping the guest
page to ensure we are not referencing a page when in range invalidation.
This call is inside a region locked with kvm-mmu_lock, which is the
same lock that is called by the KVM MMU notifier functions, thus
ensuring that no new notification can proceed while we are in the
locked region.
Signed-off-by: Bharat Bhushan bharat.bhus...@freescale.com
Acked-by: Alexander Graf ag...@suse.de
Gleb, Paolo, please queue for 3.12 directly.
Alex
---
arch/powerpc/kvm/e500_mmu_host.c | 19 +--
1 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/e500_mmu_host.c
b/arch/powerpc/kvm/e500_mmu_host.c
index ff6dd66..ae4eaf6 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -329,8 +329,14 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
int tsize = BOOK3E_PAGESZ_4K;
unsigned long tsize_pages = 0;
pte_t *ptep;
- int wimg = 0;
+ int wimg = 0, ret = 0;
pgd_t *pgdir;
+ unsigned long mmu_seq;
+ struct kvm *kvm = vcpu_e500-vcpu.kvm;
+
+ /* used to check for invalidations in progress */
+ mmu_seq = kvm-mmu_notifier_seq;
+ smp_rmb();
/*
* Translate guest physical to true physical, acquiring
@@ -458,6 +464,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
(long)gfn, pfn);
return -EINVAL;
}
+
+ spin_lock(kvm-mmu_lock);
+ if (mmu_notifier_retry(kvm, mmu_seq)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+
kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
kvmppc_e500_setup_stlbe(vcpu_e500-vcpu, gtlbe, tsize,
@@ -466,10 +479,12 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
/* Clear i-cache for new pages */
kvmppc_mmu_flush_icache(pfn);
+out:
+ spin_unlock(kvm-mmu_lock);
/* Drop refcount on page, so that mmu notifiers can clear it */
kvm_release_pfn_clean(pfn);
- return 0;
+ return ret;
}
/* XXX only map the one-one case, for now use TLB0 */
--
1.7.0.4
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Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation progress on page setup
On Wed, 2013-08-07 at 15:33 +0530, Bharat Bhushan wrote:
When the MM code is invalidating a range of pages, it calls the KVM
kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
kvm_unmap_hva_range(), which arranges to flush all the TLBs for guest pages.
However, the Linux PTEs for the range being flushed are still valid at
that point. We are not supposed to establish any new references to pages
in the range until the ...range_end() notifier gets called.
The PPC-specific KVM code doesn't get any explicit notification of that;
instead, we are supposed to use mmu_notifier_retry() to test whether we
are or have been inside a range flush notifier pair while we have been
referencing a page.
This patch calls the mmu_notifier_retry() while mapping the guest
page to ensure we are not referencing a page when in range invalidation.
This call is inside a region locked with kvm-mmu_lock, which is the
same lock that is called by the KVM MMU notifier functions, thus
ensuring that no new notification can proceed while we are in the
locked region.
Signed-off-by: Bharat Bhushan bharat.bhus...@freescale.com
---
arch/powerpc/kvm/e500_mmu_host.c | 19 +--
1 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/e500_mmu_host.c
b/arch/powerpc/kvm/e500_mmu_host.c
index ff6dd66..ae4eaf6 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -329,8 +329,14 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
int tsize = BOOK3E_PAGESZ_4K;
unsigned long tsize_pages = 0;
pte_t *ptep;
- int wimg = 0;
+ int wimg = 0, ret = 0;
pgd_t *pgdir;
+ unsigned long mmu_seq;
+ struct kvm *kvm = vcpu_e500-vcpu.kvm;
+
+ /* used to check for invalidations in progress */
+ mmu_seq = kvm-mmu_notifier_seq;
+ smp_rmb();
/*
* Translate guest physical to true physical, acquiring
@@ -458,6 +464,13 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
(long)gfn, pfn);
return -EINVAL;
}
+
+ spin_lock(kvm-mmu_lock);
+ if (mmu_notifier_retry(kvm, mmu_seq)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+
kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
kvmppc_e500_setup_stlbe(vcpu_e500-vcpu, gtlbe, tsize,
@@ -466,10 +479,12 @@ static inline int kvmppc_e500_shadow_map(struct
kvmppc_vcpu_e500 *vcpu_e500,
/* Clear i-cache for new pages */
kvmppc_mmu_flush_icache(pfn);
+out:
+ spin_unlock(kvm-mmu_lock);
/* Drop refcount on page, so that mmu notifiers can clear it */
kvm_release_pfn_clean(pfn);
- return 0;
+ return ret;
}
Acked-by: Scott Wood scottw...@freescale.com since it's currently the
standard KVM approach, though I'm not happy about the busy-waiting
aspect of it. What if we preempted the thread responsible for
decrementing mmu_notifier_count? What if we did so being a SCHED_FIFO
task of higher priority than the decrementing thread?
-Scott
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