Patchwork [01/17] KVM: PPC: Fix machine checks on 32-bit Book3S

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Submitter Paul Mackerras
Date June 29, 2011, 10:16 a.m.
Message ID <20110629101642.GB25406@bloggs.ozlabs.ibm.com>
Download mbox | patch
Permalink /patch/102560/
State Not Applicable
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Comments

Paul Mackerras - June 29, 2011, 10:16 a.m.
Commit 69acc0d3ba ("KVM: PPC: Resolve real-mode handlers through
function exports") resulted in vcpu->arch.trampoline_lowmem and
vcpu->arch.trampoline_enter ending up with kernel virtual addresses
rather than physical addresses.  This is OK on 64-bit Book3S machines,
which ignore the top 4 bits of the effective address in real mode,
but on 32-bit Book3S machines, accessing these addresses in real mode
causes machine check interrupts, as the hardware uses the whole
effective address as the physical address in real mode.

This fixes the problem by using __pa() to convert these addresses
to physical addresses.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kvm/book3s.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
Alexander Graf - July 1, 2011, 10:08 a.m.
On 29.06.2011, at 12:16, Paul Mackerras wrote:

> Commit 69acc0d3ba ("KVM: PPC: Resolve real-mode handlers through
> function exports") resulted in vcpu->arch.trampoline_lowmem and
> vcpu->arch.trampoline_enter ending up with kernel virtual addresses
> rather than physical addresses.  This is OK on 64-bit Book3S machines,
> which ignore the top 4 bits of the effective address in real mode,
> but on 32-bit Book3S machines, accessing these addresses in real mode
> causes machine check interrupts, as the hardware uses the whole
> effective address as the physical address in real mode.
> 
> This fixes the problem by using __pa() to convert these addresses
> to physical addresses.

Ouch. Thanks for the catch! I really need to include book3s_32 in my automated testing :(.


Alex

Patch

diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 73fdab8..83500fb 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -28,6 +28,7 @@ 
 #include <asm/kvm_ppc.h>
 #include <asm/kvm_book3s.h>
 #include <asm/mmu_context.h>
+#include <asm/page.h>
 #include <linux/gfp.h>
 #include <linux/sched.h>
 #include <linux/vmalloc.h>
@@ -1342,8 +1343,8 @@  struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 	vcpu_book3s->slb_nr = 64;
 
 	/* remember where some real-mode handlers are */
-	vcpu->arch.trampoline_lowmem = (ulong)kvmppc_handler_lowmem_trampoline;
-	vcpu->arch.trampoline_enter = (ulong)kvmppc_handler_trampoline_enter;
+	vcpu->arch.trampoline_lowmem = __pa(kvmppc_handler_lowmem_trampoline);
+	vcpu->arch.trampoline_enter = __pa(kvmppc_handler_trampoline_enter);
 	vcpu->arch.highmem_handler = (ulong)kvmppc_handler_highmem;
 #ifdef CONFIG_PPC_BOOK3S_64
 	vcpu->arch.rmcall = *(ulong*)kvmppc_rmcall;