[PATCH v13 01/85] KVM: Drop KVM_ERR_PTR_BAD_PAGE and instead return NULL to indicate an error

Sean Christopherson
2024-10-10T18:24:51Z

Remove KVM_ERR_PTR_BAD_PAGE and instead return NULL, as "bad page" is just
a leftover bit of weirdness from days of old when KVM stuffed a "bad" page
into the guest instead of actually handling missing pages. See commit
cea7bb21280e ("KVM: MMU: Make gfn_to_page() always safe").

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/powerpc/kvm/book3s_pr.c | 2 +-
arch/powerpc/kvm/book3s_xive_native.c | 2 +-
arch/s390/kvm/vsie.c | 2 +-
arch/x86/kvm/lapic.c | 2 +-
include/linux/kvm_host.h | 7 -------
virt/kvm/kvm_main.c | 15 ++++++---------
6 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 7b8ae509328f..d7721297b9b6 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -645,7 +645,7 @@ static void kvmppc_patch_dcbz(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)
int i;

hpage = gfn_to_page(vcpu->kvm, pte->raddr >> PAGE_SHIFT);
- if (is_error_page(hpage))
+ if (!hpage)
return;

hpage_offset = pte->raddr & ~PAGE_MASK;
diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 6e2ebbd8aaac..d9bf1bc3ff61 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -654,7 +654,7 @@ static int kvmppc_xive_native_set_queue_config(struct kvmppc_xive *xive,
}

page = gfn_to_page(kvm, gfn);
- if (is_error_page(page)) {
+ if (!page) {
srcu_read_unlock(&kvm->srcu, srcu_idx);
pr_err("Couldn't get queue page %llx!\n", kvm_eq.qaddr);
return -EINVAL;
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 89cafea4c41f..763a070f5955 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -661,7 +661,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
struct page *page;

page = gfn_to_page(kvm, gpa_to_gfn(gpa));
- if (is_error_page(page))
+ if (!page)
return -EINVAL;
*hpa = (hpa_t)page_to_phys(page) + (gpa & ~PAGE_MASK);
return 0;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2098dc689088..20526e4d6c62 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2664,7 +2664,7 @@ int kvm_alloc_apic_access_page(struct kvm *kvm)
}

page = gfn_to_page(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
- if (is_error_page(page)) {
+ if (!page) {
ret = -EFAULT;
goto out;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index db567d26f7b9..ee186a1fbaad 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -153,13 +153,6 @@ static inline bool kvm_is_error_gpa(gpa_t gpa)
return gpa == INVALID_GPA;
}

-#define KVM_ERR_PTR_BAD_PAGE (ERR_PTR(-ENOENT))
-
-static inline bool is_error_page(struct page *page)
-{
- return IS_ERR(page);
-}
-
#define KVM_REQUEST_MASK GENMASK(7,0)
#define KVM_REQUEST_NO_WAKEUP BIT(8)
#define KVM_REQUEST_WAIT BIT(9)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 05cbb2548d99..4b659a649dfa 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3078,19 +3078,14 @@ EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
*/
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
- struct page *page;
kvm_pfn_t pfn;

pfn = gfn_to_pfn(kvm, gfn);

if (is_error_noslot_pfn(pfn))
- return KVM_ERR_PTR_BAD_PAGE;
+ return NULL;

- page = kvm_pfn_to_refcounted_page(pfn);
- if (!page)
- return KVM_ERR_PTR_BAD_PAGE;
-
- return page;
+ return kvm_pfn_to_refcounted_page(pfn);
}
EXPORT_SYMBOL_GPL(gfn_to_page);

@@ -3184,7 +3179,8 @@ static void kvm_set_page_accessed(struct page *page)

void kvm_release_page_clean(struct page *page)
{
- WARN_ON(is_error_page(page));
+ if (WARN_ON(!page))
+ return;

kvm_set_page_accessed(page);
put_page(page);
@@ -3208,7 +3204,8 @@ EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);

void kvm_release_page_dirty(struct page *page)
{
- WARN_ON(is_error_page(page));
+ if (WARN_ON(!page))
+ return;

kvm_set_page_dirty(page);
kvm_release_page_clean(page);
--
2.47.0.rc1.288.g06298d1525-goog