On 28.06.2021 13:48, Jan Beulich wrote:
> At the time of d838ac2539cf ("x86: don't allow Dom0 access to the HT
> address range") documentation correctly stated that the range was
> completely fixed. For Fam17 and newer, it lives at the top of physical
> address space, though.
>
> To correctly determine the top of physical address space, we need to
> account for their physical address reduction, hence the calculation of
> paddr_bits also gets adjusted.
>
> While for paddr_bits < 40 the HT range is completely hidden, there's no
> need to suppress the range insertion in that case: It'll just have no
> real meaning.
>
> Reported-by: Igor Druzhinin <[email protected]>
> Signed-off-by: Jan Beulich <[email protected]>
> ---
> v2: Move adjustment last, to leave hap_paddr_bits unaffected. Add
> comment.
If there are any further adjustments needed here (or if the whole
situation needs to be addressed differently altogether), could
respective requests please be voiced? Or else may I please ask for
an ack?
Jan
> --- a/xen/arch/x86/cpu/common.c
> +++ b/xen/arch/x86/cpu/common.c
> @@ -349,16 +349,23 @@ void __init early_cpu_init(void)
>
> eax = cpuid_eax(0x80000000);
> if ((eax >> 16) == 0x8000 && eax >= 0x80000008) {
> + ebx = eax >= 0x8000001f ? cpuid_ebx(0x8000001f) : 0;
> eax = cpuid_eax(0x80000008);
> +
> paddr_bits = eax & 0xff;
> if (paddr_bits > PADDR_BITS)
> paddr_bits = PADDR_BITS;
> +
> vaddr_bits = (eax >> 8) & 0xff;
> if (vaddr_bits > VADDR_BITS)
> vaddr_bits = VADDR_BITS;
> +
> hap_paddr_bits = ((eax >> 16) & 0xff) ?: paddr_bits;
> if (hap_paddr_bits > PADDR_BITS)
> hap_paddr_bits = PADDR_BITS;
> +
> + /* Account for SME's physical address space reduction. */
> + paddr_bits -= (ebx >> 6) & 0x3f;
> }
>
> if (!(c->x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON)))
> --- a/xen/arch/x86/dom0_build.c
> +++ b/xen/arch/x86/dom0_build.c
> @@ -524,8 +524,11 @@ int __init dom0_setup_permissions(struct
> MSI_ADDR_DEST_ID_MASK));
> /* HyperTransport range. */
> if ( boot_cpu_data.x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON) )
> - rc |= iomem_deny_access(d, paddr_to_pfn(0xfdULL << 32),
> - paddr_to_pfn((1ULL << 40) - 1));
> + {
> + mfn = paddr_to_pfn(1UL <<
> + (boot_cpu_data.x86 < 0x17 ? 40 : paddr_bits));
> + rc |= iomem_deny_access(d, mfn - paddr_to_pfn(3UL << 32), mfn - 1);
> + }
>
> /* Remove access to E820_UNUSABLE I/O regions above 1MB. */
> for ( i = 0; i < e820.nr_map; i++ )
>
>
