[PULL 19/51] KVM: PPC: Book3S PR: Correct errors in H_ENTER implementation

Alexander Graf
2013-10-31T21:18:44Z

The implementation of H_ENTER in PR KVM has some errors:

* With H_EXACT not set, if the HPTEG is full, we return H_PTEG_FULL
as the return value of kvmppc_h_pr_enter, but the caller is expecting
one of the EMULATE_* values. The H_PTEG_FULL needs to go in the
guest's R3 instead.

* With H_EXACT set, if the selected HPTE is already valid, the H_ENTER
call should return a H_PTEG_FULL error.

This fixes these errors and also makes it write only the selected HPTE,
not the whole group, since only the selected HPTE has been modified.
This also micro-optimizes the calculations involving pte_index and i.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/powerpc/kvm/book3s_pr_papr.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr_papr.c b/arch/powerpc/kvm/book3s_pr_papr.c
index da0e0bc..38f1899 100644
--- a/arch/powerpc/kvm/book3s_pr_papr.c
+++ b/arch/powerpc/kvm/book3s_pr_papr.c
@@ -21,6 +21,8 @@
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>

+#define HPTE_SIZE 16 /* bytes per HPT entry */
+
static unsigned long get_pteg_addr(struct kvm_vcpu *vcpu, long pte_index)
{
struct kvmppc_vcpu_book3s *vcpu_book3s = to_book3s(vcpu);
@@ -40,32 +42,39 @@ static int kvmppc_h_pr_enter(struct kvm_vcpu *vcpu)
long pte_index = kvmppc_get_gpr(vcpu, 5);
unsigned long pteg[2 * 8];
unsigned long pteg_addr, i, *hpte;
+ long int ret;

+ i = pte_index & 7;
pte_index &= ~7UL;
pteg_addr = get_pteg_addr(vcpu, pte_index);

copy_from_user(pteg, (void __user *)pteg_addr, sizeof(pteg));
hpte = pteg;

+ ret = H_PTEG_FULL;
if (likely((flags & H_EXACT) == 0)) {
- pte_index &= ~7UL;
for (i = 0; ; ++i) {
if (i == 8)
- return H_PTEG_FULL;
+ goto done;
if ((*hpte & HPTE_V_VALID) == 0)
break;
hpte += 2;
}
} else {
- i = kvmppc_get_gpr(vcpu, 5) & 7UL;
hpte += i * 2;
+ if (*hpte & HPTE_V_VALID)
+ goto done;
}

hpte[0] = kvmppc_get_gpr(vcpu, 6);
hpte[1] = kvmppc_get_gpr(vcpu, 7);
- copy_to_user((void __user *)pteg_addr, pteg, sizeof(pteg));
- kvmppc_set_gpr(vcpu, 3, H_SUCCESS);
+ pteg_addr += i * HPTE_SIZE;
+ copy_to_user((void __user *)pteg_addr, hpte, HPTE_SIZE);
kvmppc_set_gpr(vcpu, 4, pte_index | i);
+ ret = H_SUCCESS;
+
+ done:
+ kvmppc_set_gpr(vcpu, 3, ret);

return EMULATE_DONE;
}
--
1.8.1.4