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riscv: kvm: Skip TLB flush when G-stage PTE becomes valid with Svvptc

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The gstage_tlb_flush() in the kvm_riscv_gstage_set_pte() is not needed
when an invalid G-stage PTE becomes valid and Svvptc extension is available
because new valid PTEs become visible to the page-table walker within a
bounded time.

Assisted-by: YuanSheng: deepseek-v4-pro
Co-developed-by: Quan Zhou <zhouquan@iscas.ac.cn>
Signed-off-by: Quan Zhou <zhouquan@iscas.ac.cn>
Signed-off-by: Dylan.Wu <fredwudi0305@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260701075239.95542-1-fredwudi0305@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Dylan.Wu
2026-07-01 03:52:39 -04:00
committed by Anup Patel
parent 0cc15f2c7a
commit 1cc935ec2d
1 changed files with 5 additions and 1 deletions
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6
arch/riscv/kvm/gstage.c
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@@ -5,11 +5,13 @@
*/
#include <linux/bitops.h>
#include <linux/cpufeature.h>
#include <linux/errno.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/pgtable.h>
#include <asm/kvm_gstage.h>
#include <asm/hwcap.h>
#ifdef CONFIG_64BIT
unsigned long kvm_riscv_gstage_max_pgd_levels __ro_after_init = 3;
@@ -171,8 +173,10 @@ int kvm_riscv_gstage_set_pte(struct kvm_gstage *gstage,
}
if (pte_val(*ptep) != pte_val(map->pte)) {
bool was_invalid = !pte_val(*ptep);
set_pte(ptep, map->pte);
if (gstage_pte_leaf(ptep))
if (gstage_pte_leaf(ptep) &&
!(was_invalid && riscv_has_extension_unlikely(RISCV_ISA_EXT_SVVPTC)))
gstage_tlb_flush(gstage, current_level, map->addr);
}