KVM: PPC: Book3S HV: Restructure HPT entry creation code

This restructures the code that creates HPT (hashed page table)
entries so that it can be called in situations where we don't have a
struct vcpu pointer, only a struct kvm pointer.  It also fixes a bug
where kvmppc_map_vrma() would corrupt the guest R4 value.

Most of the work of kvmppc_virtmode_h_enter is now done by a new
function, kvmppc_virtmode_do_h_enter, which itself calls another new
function, kvmppc_do_h_enter, which contains most of the old
kvmppc_h_enter.  The new kvmppc_do_h_enter takes explicit arguments
for the place to return the HPTE index, the Linux page tables to use,
and whether it is being called in real mode, thus removing the need
for it to have the vcpu as an argument.

Currently kvmppc_map_vrma creates the VRMA (virtual real mode area)
HPTEs by calling kvmppc_virtmode_h_enter, which is designed primarily
to handle H_ENTER hcalls from the guest that need to pin a page of
memory.  Since H_ENTER returns the index of the created HPTE in R4,
kvmppc_virtmode_h_enter updates the guest R4, corrupting the guest R4
in the case when it gets called from kvmppc_map_vrma on the first
VCPU_RUN ioctl.  With this, kvmppc_map_vrma instead calls
kvmppc_virtmode_do_h_enter with the address of a dummy word as the
place to store the HPTE index, thus avoiding corrupting the guest R4.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 17 insertions, 10 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 5e06e3153888..362dffe4db10 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -103,14 +103,14 @@ static void remove_revmap_chain(struct kvm *kvm, long pte_index,
 	unlock_rmap(rmap);
 }
 
-static pte_t lookup_linux_pte(struct kvm_vcpu *vcpu, unsigned long hva,
+static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
 			      int writing, unsigned long *pte_sizep)
 {
 	pte_t *ptep;
 	unsigned long ps = *pte_sizep;
 	unsigned int shift;
 
-	ptep = find_linux_pte_or_hugepte(vcpu->arch.pgdir, hva, &shift);
+	ptep = find_linux_pte_or_hugepte(pgdir, hva, &shift);
 	if (!ptep)
 		return __pte(0);
 	if (shift)
@@ -130,10 +130,10 @@ static inline void unlock_hpte(unsigned long *hpte, unsigned long hpte_v)
 	hpte[0] = hpte_v;
 }
 
-long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
-		    long pte_index, unsigned long pteh, unsigned long ptel)
+long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
+		       long pte_index, unsigned long pteh, unsigned long ptel,
+		       pgd_t *pgdir, bool realmode, unsigned long *pte_idx_ret)
 {
-	struct kvm *kvm = vcpu->kvm;
 	unsigned long i, pa, gpa, gfn, psize;
 	unsigned long slot_fn, hva;
 	unsigned long *hpte;
@@ -147,7 +147,6 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 	unsigned int writing;
 	unsigned long mmu_seq;
 	unsigned long rcbits;
-	bool realmode = vcpu->arch.vcore->vcore_state == VCORE_RUNNING;
 
 	psize = hpte_page_size(pteh, ptel);
 	if (!psize)
@@ -201,7 +200,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 
 		/* Look up the Linux PTE for the backing page */
 		pte_size = psize;
-		pte = lookup_linux_pte(vcpu, hva, writing, &pte_size);
+		pte = lookup_linux_pte(pgdir, hva, writing, &pte_size);
 		if (pte_present(pte)) {
 			if (writing && !pte_write(pte))
 				/* make the actual HPTE be read-only */
@@ -210,6 +209,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 			pa = pte_pfn(pte) << PAGE_SHIFT;
 		}
 	}
+
 	if (pte_size < psize)
 		return H_PARAMETER;
 	if (pa && pte_size > psize)
@@ -297,7 +297,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 		lock_rmap(rmap);
 		/* Check for pending invalidations under the rmap chain lock */
 		if (kvm->arch.using_mmu_notifiers &&
-		    mmu_notifier_retry(vcpu->kvm, mmu_seq)) {
+		    mmu_notifier_retry(kvm, mmu_seq)) {
 			/* inval in progress, write a non-present HPTE */
 			pteh |= HPTE_V_ABSENT;
 			pteh &= ~HPTE_V_VALID;
@@ -318,10 +318,17 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 	hpte[0] = pteh;
 	asm volatile("ptesync" : : : "memory");
 
-	vcpu->arch.gpr[4] = pte_index;
+	*pte_idx_ret = pte_index;
 	return H_SUCCESS;
 }
-EXPORT_SYMBOL_GPL(kvmppc_h_enter);
+EXPORT_SYMBOL_GPL(kvmppc_do_h_enter);
+
+long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
+		    long pte_index, unsigned long pteh, unsigned long ptel)
+{
+	return kvmppc_do_h_enter(vcpu->kvm, flags, pte_index, pteh, ptel,
+				 vcpu->arch.pgdir, true, &vcpu->arch.gpr[4]);
+}
 
 #define LOCK_TOKEN	(*(u32 *)(&get_paca()->lock_token))