Hi Nikunj,
On 18.01.2022 12:06, Nikunj A Dadhania wrote:
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Pin the memory for the data being passed to launch_update_data()
because it gets encrypted before the guest is first run and must
not be moved which would corrupt it.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
[ * Changed hva_to_gva() to take an extra argument and return gpa_t.
* Updated sev_pin_memory_in_mmu() error handling.
* As pinning/unpining pages is handled within MMU, removed
{get,put}_user(). ]
Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
---
arch/x86/kvm/svm/sev.c | 122 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 119 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 14aeccfc500b..1ae714e83a3c 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -22,6 +22,7 @@
#include <asm/trapnr.h>
#include <asm/fpu/xcr.h>
+#include "mmu.h"
#include "x86.h"
#include "svm.h"
#include "svm_ops.h"
@@ -490,6 +491,110 @@ static unsigned long get_num_contig_pages(unsigned long idx,
return pages;
}
+#define SEV_PFERR_RO (PFERR_USER_MASK)
+#define SEV_PFERR_RW (PFERR_WRITE_MASK | PFERR_USER_MASK)
+
+static struct kvm_memory_slot *hva_to_memslot(struct kvm *kvm,
+ unsigned long hva)
+{
+ struct kvm_memslots *slots = kvm_memslots(kvm);
+ struct kvm_memory_slot *memslot;
+ int bkt;
+
+ kvm_for_each_memslot(memslot, bkt, slots) {
+ if (hva >= memslot->userspace_addr &&
+ hva < memslot->userspace_addr +
+ (memslot->npages << PAGE_SHIFT))
+ return memslot;
+ }
+
+ return NULL;
+}
We have kvm_for_each_memslot_in_hva_range() now, please don't do a linear
search through memslots.
You might need to move the aforementioned macro from kvm_main.c to some
header file, though.
+static gpa_t hva_to_gpa(struct kvm *kvm, unsigned long hva, bool *ro)
+{
+ struct kvm_memory_slot *memslot;
+ gpa_t gpa_offset;
+
+ memslot = hva_to_memslot(kvm, hva);
+ if (!memslot)
+ return UNMAPPED_GVA;
+
+ *ro = !!(memslot->flags & KVM_MEM_READONLY);
+ gpa_offset = hva - memslot->userspace_addr;
+ return ((memslot->base_gfn << PAGE_SHIFT) + gpa_offset);
+}
+
+static struct page **sev_pin_memory_in_mmu(struct kvm *kvm, unsigned long addr,
+ unsigned long size,
+ unsigned long *npages)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ struct kvm_vcpu *vcpu;
+ struct page **pages;
+ unsigned long i;
+ u32 error_code;
+ kvm_pfn_t pfn;
+ int idx, ret = 0;
+ gpa_t gpa;
+ bool ro;
+
+ pages = sev_alloc_pages(sev, addr, size, npages);
+ if (IS_ERR(pages))
+ return pages;
+
+ vcpu = kvm_get_vcpu(kvm, 0);
+ if (mutex_lock_killable(&vcpu->mutex)) {
+ kvfree(pages);
+ return ERR_PTR(-EINTR);
+ }
+
+ vcpu_load(vcpu);
+ idx = srcu_read_lock(&kvm->srcu);
+
+ kvm_mmu_load(vcpu);
+
+ for (i = 0; i < *npages; i++, addr += PAGE_SIZE) {
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ if (need_resched())
+ cond_resched();
+
+ gpa = hva_to_gpa(kvm, addr, &ro);
+ if (gpa == UNMAPPED_GVA) {
+ ret = -EFAULT;
+ break;
+ }
This function is going to have worst case O(n²) complexity if called with
the whole VM memory (or O(n * log(n)) when hva_to_memslot() is modified
to use kvm_for_each_memslot_in_hva_range()).
That's really bad for something that can be done in O(n) time - look how
kvm_for_each_memslot_in_gfn_range() does it over gfns.
Thanks,
Maciej
