Re: [PATCH v3 51/75] x86/sev-es: Handle MMIO events

Joerg Roedel
2020-06-11T12:40:08Z

On Tue, May 19, 2020 at 11:32:02PM -0700, Sean Christopherson wrote:
> '0' is a valid physical address. It happens to be reserved in the kernel
> thanks to L1TF, but using '0' as an error code is ugly. Not to mention
> none of the callers actually check the result.

Right, I changed the function to better handle error cases and added
checks to the call-sites. It looks like below now:

static bool vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
unsigned long vaddr, phys_addr_t *paddr)
{
unsigned long va = (unsigned long)vaddr;
unsigned int level;
phys_addr_t pa;
pgd_t *pgd;
pte_t *pte;

pgd = pgd_offset(current->active_mm, va);
pte = lookup_address_in_pgd(pgd, va, &level);
if (!pte) {
ctxt->fi.vector = X86_TRAP_PF;
ctxt->fi.cr2 = vaddr;
ctxt->fi.error_code = 0;

if (user_mode(ctxt->regs))
ctxt->fi.error_code |= X86_PF_USER;

return false;
}

pa = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
pa |= va & ~page_level_mask(level);

*paddr = pa;

return true;
}