On Wed, Jul 10, 2019 at 08:13:11PM +0000, Singh, Brijesh wrote:
> Subject: Re: [PATCH v3 10/11] mm: x86: Invoke hypercall when page encryption status is changed
Subject prefix: "x86/mm: Invoke ..."
git log <filename> would usually show you how the prefixing should look
like.
> Invoke a hypercall when a memory region is changed from encrypted ->
> decrypted and vice versa. Hypervisor need to know the page encryption
> status during the guest migration.
>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Cc: x86@xxxxxxxxxx
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> ---
> arch/x86/include/asm/mem_encrypt.h | 3 ++
> arch/x86/mm/mem_encrypt.c | 45 +++++++++++++++++++++++++++++-
> arch/x86/mm/pageattr.c | 15 ++++++++++
> 3 files changed, 62 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
> index 0c196c47d621..6e654ab5a8e4 100644
> --- a/arch/x86/include/asm/mem_encrypt.h
> +++ b/arch/x86/include/asm/mem_encrypt.h
> @@ -94,4 +94,7 @@ extern char __start_bss_decrypted[], __end_bss_decrypted[], __start_bss_decrypte
>
> #endif /* __ASSEMBLY__ */
>
> +extern void set_memory_enc_dec_hypercall(unsigned long vaddr,
> + unsigned long size, bool enc);
> +
> #endif /* __X86_MEM_ENCRYPT_H__ */
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index e0df96fdfe46..f3fda1de2869 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -15,6 +15,7 @@
> #include <linux/dma-direct.h>
> #include <linux/swiotlb.h>
> #include <linux/mem_encrypt.h>
> +#include <linux/kvm_para.h>
>
> #include <asm/tlbflush.h>
> #include <asm/fixmap.h>
> @@ -25,6 +26,7 @@
> #include <asm/processor-flags.h>
> #include <asm/msr.h>
> #include <asm/cmdline.h>
> +#include <asm/kvm_para.h>
>
> #include "mm_internal.h"
>
> @@ -192,6 +194,45 @@ void __init sme_early_init(void)
> swiotlb_force = SWIOTLB_FORCE;
> }
>
> +void set_memory_enc_dec_hypercall(unsigned long vaddr, unsigned long sz, bool enc)
> +{
> + unsigned long vaddr_end, vaddr_next;
> +
> + vaddr_end = vaddr + sz;
> +
> + for (; vaddr < vaddr_end; vaddr = vaddr_next) {
> + int psize, pmask, level;
> + unsigned long pfn;
> + pte_t *kpte;
> +
> + kpte = lookup_address(vaddr, &level);
> + if (!kpte || pte_none(*kpte))
> + return;
> +
> + switch (level) {
> + case PG_LEVEL_4K:
> + pfn = pte_pfn(*kpte);
> + break;
> + case PG_LEVEL_2M:
> + pfn = pmd_pfn(*(pmd_t *)kpte);
> + break;
> + case PG_LEVEL_1G:
> + pfn = pud_pfn(*(pud_t *)kpte);
> + break;
> + default:
> + return;
> + }
> +
> + psize = page_level_size(level);
> + pmask = page_level_mask(level);
> +
> + kvm_sev_hypercall3(KVM_HC_PAGE_ENC_STATUS,
> + pfn << PAGE_SHIFT, psize >> PAGE_SHIFT, enc);
> +
> + vaddr_next = (vaddr & pmask) + psize;
> + }
> +}
> +
> static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
> {
> pgprot_t old_prot, new_prot;
> @@ -249,12 +290,13 @@ static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
> static int __init early_set_memory_enc_dec(unsigned long vaddr,
> unsigned long size, bool enc)
> {
> - unsigned long vaddr_end, vaddr_next;
> + unsigned long vaddr_end, vaddr_next, start;
> unsigned long psize, pmask;
> int split_page_size_mask;
> int level, ret;
> pte_t *kpte;
>
> + start = vaddr;
> vaddr_next = vaddr;
> vaddr_end = vaddr + size;
>
> @@ -309,6 +351,7 @@ static int __init early_set_memory_enc_dec(unsigned long vaddr,
>
> ret = 0;
>
> + set_memory_enc_dec_hypercall(start, size, enc);
That function iterates the same way over the virtual addresses as
early_set_memory_enc_dec() does. Please call kvm_sev_hypercall3(),
wrapped of course, directly from early_set_memory_enc_dec(), for
each iteration of the loop instead of iterating over all the virtual
addresses a second time in set_memory_enc_dec_hypercall().
--
Regards/Gruss,
Boris.
SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 247165, AG München
