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authorLinus Torvalds <torvalds@linux-foundation.org>2020-12-16 13:51:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-16 13:51:34 -0800
commit007c74e16c1aac9f5c93b372a054f7f11ede8628 (patch)
treebcd838d799379a1289160183674ea485c7dc4154 /arch/x86
parent009bd55dfcc857d8b00a5bbb17a8db060317af6f (diff)
parente998879d4fb7991856916972168cf27c0d86ed12 (diff)
downloadlinux-007c74e16c1aac9f5c93b372a054f7f11ede8628.tar.bz2
Merge branch 'stable/for-linus-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb
Pull swiotlb update from Konrad Rzeszutek Wilk: "A generic (but for right now engaged only with AMD SEV) mechanism to adjust a larger size SWIOTLB based on the total memory of the SEV guests which right now require the bounce buffer for interacting with the outside world. Normal knobs (swiotlb=XYZ) still work" * 'stable/for-linus-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb: x86,swiotlb: Adjust SWIOTLB bounce buffer size for SEV guests
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/mem_encrypt.h2
-rw-r--r--arch/x86/kernel/setup.c6
-rw-r--r--arch/x86/mm/mem_encrypt.c31
3 files changed, 39 insertions, 0 deletions
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 2f62bbdd9d12..31c4df123aa0 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -37,6 +37,7 @@ void __init sme_map_bootdata(char *real_mode_data);
void __init sme_unmap_bootdata(char *real_mode_data);
void __init sme_early_init(void);
+void __init sev_setup_arch(void);
void __init sme_encrypt_kernel(struct boot_params *bp);
void __init sme_enable(struct boot_params *bp);
@@ -69,6 +70,7 @@ static inline void __init sme_map_bootdata(char *real_mode_data) { }
static inline void __init sme_unmap_bootdata(char *real_mode_data) { }
static inline void __init sme_early_init(void) { }
+static inline void __init sev_setup_arch(void) { }
static inline void __init sme_encrypt_kernel(struct boot_params *bp) { }
static inline void __init sme_enable(struct boot_params *bp) { }
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a23130c86bdd..740f3bdb3f61 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1049,6 +1049,12 @@ void __init setup_arch(char **cmdline_p)
memblock_set_current_limit(ISA_END_ADDRESS);
e820__memblock_setup();
+ /*
+ * Needs to run after memblock setup because it needs the physical
+ * memory size.
+ */
+ sev_setup_arch();
+
reserve_bios_regions();
efi_fake_memmap();
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index bc0833713be9..c79e5736ab2b 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -198,6 +198,37 @@ void __init sme_early_init(void)
swiotlb_force = SWIOTLB_FORCE;
}
+void __init sev_setup_arch(void)
+{
+ phys_addr_t total_mem = memblock_phys_mem_size();
+ unsigned long size;
+
+ if (!sev_active())
+ return;
+
+ /*
+ * For SEV, all DMA has to occur via shared/unencrypted pages.
+ * SEV uses SWIOTLB to make this happen without changing device
+ * drivers. However, depending on the workload being run, the
+ * default 64MB of SWIOTLB may not be enough and SWIOTLB may
+ * run out of buffers for DMA, resulting in I/O errors and/or
+ * performance degradation especially with high I/O workloads.
+ *
+ * Adjust the default size of SWIOTLB for SEV guests using
+ * a percentage of guest memory for SWIOTLB buffers.
+ * Also, as the SWIOTLB bounce buffer memory is allocated
+ * from low memory, ensure that the adjusted size is within
+ * the limits of low available memory.
+ *
+ * The percentage of guest memory used here for SWIOTLB buffers
+ * is more of an approximation of the static adjustment which
+ * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
+ */
+ size = total_mem * 6 / 100;
+ size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
+ swiotlb_adjust_size(size);
+}
+
static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
{
pgprot_t old_prot, new_prot;