On Mon, 20 Feb 2023 12:38:44 -0600 Michael Roth <michael.roth@xxxxxxx> wrote: > From: Ashish Kalra <ashish.kalra@xxxxxxx> > > Implement a workaround for an SNP erratum where the CPU will incorrectly > signal an RMP violation #PF if a hugepage (2mb or 1gb) collides with the > RMP entry of the VMSAVE target page. > > When SEV-SNP is globally enabled, the CPU marks the VMSAVE target page > as "InUse" while the VMSAVE instruction is executing. If another > CPU writes to a different page in the same 2MB region while the VMSAVE > is executing, the CPU will throw an RMP violation #PF. > > Use the snp safe generic allocator for allocating the VMSA target > page which will ensure that the page returned is not a hugepage, as it > is already being used for the allocating the VMCB, VMSA and AVIC backing > page. > This should be merged with patch where implements the snp_safe_alloc_page(). > Co-developed-by: Marc Orr <marcorr@xxxxxxxxxx> > Signed-off-by: Marc Orr <marcorr@xxxxxxxxxx> > Reported-by: Alper Gun <alpergun@xxxxxxxxxx> > Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx> > Signed-off-by: Michael Roth <michael.roth@xxxxxxx> > --- > arch/x86/kvm/svm/svm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 3fe5f13b5f3a..8bda31a61757 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -665,7 +665,7 @@ static int svm_cpu_init(int cpu) > int ret = -ENOMEM; > > memset(sd, 0, sizeof(struct svm_cpu_data)); > - sd->save_area = alloc_page(GFP_KERNEL | __GFP_ZERO); > + sd->save_area = snp_safe_alloc_page(NULL); > if (!sd->save_area) > return ret; >
